Is pesto vegan?

Pesto is a good example of a dish where the animal ingredient is authentic rather than incidental. Pesto alla genovese is defined by basil, pine nuts, garlic, olive oil, salt and hard cheese - normally Parmigiano-Reggiano, frequently with Pecorino Sardo alongside it. The cheese is not a topping; it is emulsified into the sauce and contributes both salt and body. Remove it and you have to rebalance the recipe rather than simply leave a gap.

There is a second layer that catches even vegetarians. Parmigiano-Reggiano is a DOP product and its production rules require calf rennet, an enzyme taken from the stomach lining of slaughtered calves. Pecorino Romano and Pecorino Sardo have equivalent requirements using lamb rennet. So genuine Parmigiano is not vegetarian, let alone vegan - a fact that surprises a lot of people who have been eating it for years under the assumption that cheese is a vegetarian food.

Commercial jarred pesto is more variable and slightly more forgiving. Cheaper jars often use generic "hard cheese" or "medium-fat hard cheese" rather than certified Parmigiano, and some of those are made with microbial rennet, which is vegetarian. That still leaves the milk, so it remains firmly non-vegan. The practical upshot: a jar being vegetarian tells you nothing about it being vegan, and you have to read the list either way.

Vegan pesto has become genuinely easy to buy. Sacla, Zest, Rubies in the Rubble and a long list of own-brand ranges make versions that replace the cheese with nutritional yeast, cashews, or a vegan hard-cheese analogue. Quality varies more than with dairy pesto, so it is worth trying a couple. Read the front carefully though - "dairy-free" and "vegan" are not the same claim, and red or sun-dried tomato pesto sometimes contains milk powder even when the green version in the same range does not.

Making it yourself sidesteps everything and takes about five minutes. Basil, garlic, olive oil, toasted pine nuts (or cheaper walnuts, sunflower seeds or cashews), a generous amount of nutritional yeast for the savoury note, salt, and a squeeze of lemon to keep the colour. The nutritional yeast is doing the Parmesan's job; do not skip it or the result tastes flat rather than fresh.