Should You Make Pesto in a Mortar and Pestle or Food Processor?

A mortar and pestle gives you exceptional control and a beautiful texture, while a food processor is faster and considerably more practical for everyday pesto. We use both, but there’s absolutely nothing wrong with reaching for the food processor.

The traditional mortar-and-pestle technique crushes the basil rather than chopping it with blades. Crushing ruptures the plant cells and releases the basil’s aromatic compounds while allowing you to control the texture gradually. You also avoid generating as much heat as a food processor can when it runs for too long.

But we’re also chefs who live in the real world. If using a food processor means you’re making homemade pesto on a Tuesday night, use the food processor.

The trick is to pulse rather than pulverize. Short bursts give you control, reduce heat buildup and help preserve some texture.

Why Can Pesto Turn Bitter in a Food Processor?

Pesto can taste bitter when ingredients are over-processed, particularly strongly flavoured extra virgin olive oil. Using short pulses and adding the oil toward the end gives you more control.

Extra virgin olive oil naturally contains bitter and peppery compounds. That’s usually a good thing and part of what makes quality olive oil interesting, but aggressive blending can make those characteristics more noticeable.

The basil itself can also suffer when you process it excessively. Fast-moving blades generate heat and expose more of the leaves to oxygen, neither of which helps that fresh basil flavour.

Our solution is simple. Do most of the chopping before adding the oil, then blend only as much as necessary once the olive oil goes in.

How Do You Keep Basil Pesto Green?

Work quickly, avoid overheating the basil and limit its exposure to air if you want pesto to stay vibrant. A little lemon juice can also help, although we use it primarily for flavour rather than relying on it as a colour fix.

Once you bruise or chop basil leaves, enzymes inside the plant come into contact with oxygen and browning begins. It’s similar to what happens when you cut an apple, although the chemistry isn’t exactly the same.

Heat can speed up deterioration too, which gives us another reason not to leave the food processor running unnecessarily.

If you’re storing pesto, press a piece of reusable food wrap directly against the surface or cover it with a thin layer of olive oil before sealing the container. Reducing contact with oxygen helps slow down discolouration.

And don’t panic if your homemade pesto darkens slightly. Bright green is beautiful, but flavour matters more than Instagram.

Why Freshly Grated Parmesan Makes Better Pesto

Freshly grated Parmesan or Grana Padano melts into pesto more evenly and gives you a cleaner, richer flavour than many pre-grated cheeses. It also lets you control the texture of the finished sauce.

Parmesan brings salt, umami and richness, so it does considerably more than simply make the pesto cheesy. Because the cheese is already salty, we recommend adding your salt conservatively and adjusting after everything has been combined.

Grana Padano is also excellent here. It tends to be slightly milder than Parmigiano Reggiano and can be a little less expensive, which fits nicely with our pumpkin seed philosophy.

Great pesto should taste luxurious. It doesn’t have to cost a fortune.

How to Use Basil Pesto with Pasta

For pesto pasta, loosen the pesto with a little hot pasta water before tossing it with freshly cooked pasta. Avoid aggressively cooking the pesto in a frying pan because high heat dulls the fresh basil flavour.

This is one of the most useful pesto tricks we can give you.

Before draining your pasta, scoop out a cup of that cloudy, starchy pasta water. Put your pesto into a large bowl, add a splash of pasta water and stir. Add the hot pasta and toss, adding more water as necessary until the pesto becomes glossy and coats the noodles.

The starch in the pasta water helps bring the olive oil, cheese and water together into a creamier sauce. You get beautifully coated pasta without adding cream.

And please don’t drain your pasta, dump pesto into a screaming-hot frying pan and cook it for five minutes. You just went to all that trouble to preserve the flavour of fresh basil.

Let the hot pasta warm the pesto.

What Else Can You Do with Basil Pesto?

Basil pesto is far more useful than a pasta sauce. Keep a jar in the refrigerator and you have an instant finishing sauce for grilled meat, vegetables, sandwiches, eggs and plenty more.

We use it on grilled chicken, steak and fish, spoon it onto roasted vegetables, spread it inside sandwiches and wraps, or stir a spoonful into mayonnaise or Greek yogurt for a quick sauce. It’s fantastic with tomatoes and fresh mozzarella and equally good dolloped onto soup just before serving.

You can also spread it onto pizza after baking, stir it through warm potatoes, add it to scrambled eggs or spoon it over a grain bowl. Essentially, if dinner looks like it needs something green and delicious, pesto is a pretty good answer.

Jody and Kirstie’s Hot Tips

• Toast your pumpkin seeds. A few minutes in a dry pan gives them significantly more flavour.
• Cool the seeds before blending. There’s no reason to introduce extra heat to fresh basil.
• Use the basil leaves and tender stems. You don’t need to painstakingly remove every tiny stem.
• Pulse, don’t purée. Pesto should have texture.
• Add the olive oil toward the end. This reduces unnecessary processing and gives you better control over consistency.
• Grate your own cheese. It incorporates better and tastes better.
• Save your pasta water. A splash turns pesto into a silky pasta sauce without cream.
• Freeze the summer surplus. Future January-you will be extremely pleased with August-you.

Substitutions

Pesto is a technique as much as it is a recipe, so you can change the greens, seeds, cheese and acidity while keeping the basic structure intact.

If you don’t have pumpkin seeds, pine nuts certainly work, as do walnuts, almonds or sunflower seeds. You can replace some or all of the basil with parsley, arugula or other tender herbs and greens.

Pecorino can replace Parmesan if you want something sharper and saltier. If you’re making a dairy-free pesto, omit the cheese and adjust the salt and acidity to compensate. Nutritional yeast can add savoury flavour, although it will create a different pesto rather than an exact Parmesan replacement.

What to Know and Avoid When Making Pesto

The biggest pesto mistakes are using tired basil, over-processing the sauce and forgetting to taste before adding more salt. Start with good ingredients and stop blending sooner than you think.

Avoid washing basil immediately before making pesto unless it genuinely needs it. If you do wash it, dry it thoroughly. Excess water dilutes the sauce and wet basil doesn’t store as well.

Don’t assume more garlic means better pesto either. Raw garlic becomes powerful very quickly, and our goal is to taste basil first. One clove gives us plenty.

Finally, don’t treat the ingredient measurements as handcuffs. Basil varies, cheeses vary and even olive oils behave differently. The recipe gets you very close, then your palate finishes the job.

How to Store Basil Pesto

Fresh basil pesto keeps best in an airtight container in the refrigerator with its surface protected from air. For longer storage, freeze it in small portions so you can thaw only what you need.

For refrigerator storage, transfer the pesto to a clean container and smooth the surface. Add a thin layer of olive oil or place food wrap directly against the pesto before covering. For best quality, we’d use refrigerated homemade pesto within several days.

Pesto also freezes extremely well. Spoon it into an ice cube tray or small containers, freeze until solid, then transfer the portions to a freezer bag or container. Those little pesto portions are perfect for pasta, soups and sauces when basil season is long gone.

Basil Pesto FAQ

Can I make pesto without pine nuts?

Absolutely. We use toasted pumpkin seeds in our basil pesto. They’re affordable, readily available and give the pesto excellent richness and texture without overpowering the basil.  In fact, you can even make pesto without basil! 

Do pumpkin seeds taste different from pine nuts in pesto?

Yes, slightly. Pumpkin seeds have a mild earthy, nutty flavour, while pine nuts are softer and more buttery. Once combined with basil, Parmesan, garlic and olive oil, pumpkin seeds make a fantastic pesto in their own right.

Should you toast pumpkin seeds for pesto?

We recommend it. Toasting develops deeper nutty flavours and only takes a few minutes. Let the seeds cool before adding them to your basil.

Why is my homemade pesto bitter?

Over-processing strongly flavoured extra virgin olive oil can emphasize its bitter notes. Use short pulses, add the olive oil toward the end and stop processing as soon as you reach the texture you want.

Can you freeze basil pesto?

Yes. Pesto freezes beautifully. Freeze it in small portions or ice cube trays so you can thaw exactly what you need for pasta, sauces or soups.

Should pesto be heated?

We prefer not to cook basil pesto directly over high heat. For pasta, loosen it with pasta water and toss it with freshly cooked noodles. The heat from the pasta warms the pesto while preserving its fresh basil flavour.

Key Takeaways

• Homemade basil pesto takes about 10 minutes and tastes dramatically fresher than most store-bought versions.
• We prefer toasted pumpkin seeds to pine nuts because they’re delicious, affordable and easy to find.
• Pulse your pesto rather than over-processing it to preserve texture and fresh basil flavour.
• Add olive oil toward the end and use pasta water to turn pesto into a silky pasta sauce.
• Make extra while basil is abundant because pesto freezes beautifully.

If you want to become a more confident cook rather than simply collect more recipes, check out our on-demand cooking classes. We teach the techniques and science behind what you’re making, and you can cook along at your own pace. No Cook is Left Behind.

About Jody and Kirstie

 

Jody O’Malley and Kirstie Herbstreit are the Red Seal certified chef co-owners of The Culinary Studio in Waterloo, Ontario. Jody is a Stratford Chefs School graduate (2002) and Kirstie trained at SAIT in Calgary (2003). Together, they bring over 20 years of professional cooking experience and 15 years building one of Canada’s leading culinary education businesses. They teach home cooks the science and techniques behind great food, not just the recipes, and co-host the Chef Over Your Shoulder podcast alongside Amy Schlueter.