by Michael Hawkins
Traditionally speaking, the only difference between green and red pesto is that the former gets its trademark colour from basil, while the latter gets its fiery colour from tomatoes. There are, however, more and more pestos being launched that get their red and green colours from completely different herbs and vegetables.
Once upon a time, there was only green pesto
For hundreds of years, there was only one recognised pesto recipe, the one that hails from Genoa in Italy and which contains basil, olive oil, pine nuts, salt, garlic, Parmesan, and pecorino. As this vibrant green sauce travelled through international trade routes, the recipe gradually developed cultural and geographical nuances, with cooks from different regions incorporating or removing ingredients based on what was readily available to them.
The Sicilians introduced red pesto
Most famously, when the sauce reached Sicily, cooks there started to incorporate their world-class tomatoes, which is still the main way that most red pestos get their colour.
There are still plenty of green pesto traditionalists
There's no shortage of Italians who vigorously defend the original pesto recipe and who argue there will only ever be one recipe that has the right to call itself "pesto." They accept that the sauce can be adapted into an equally tasty product, but they believe that if the recipe veers at all from the original, it cannot be called pesto.
Nowadays, the red and green colours don't just come from tomatoes and basil
These days, you can find plenty of pesto sauces that get their red and green colours from different ingredients entirely. Barilla, the world's biggest pasta company, has a huge portfolio of sauces that they sell under the "pesto" umbrella. Rocket is responsible for the bright green colour of one of its most popular products, while red pepper and chilli are responsible for the red colour in one of their other recipes. It doesn't stop there, though. The colours of some of their other sauces are influenced by a whole host of non-traditional ingredients, including onion, ricotta, walnuts, and even balsamic vinegar.
The world of pesto beyond just red and green
Further afield, it doesn't just stop at red and green; you can find pestos that span the whole colour spectrum. White pesto omits herbs entirely, while black olive pesto can be as dark as the night. Beetroot pesto is probably the most outlandish of the lot, with a colour so pink that it almost looks radioactive.
