Wash the basil leaves taking care not to damage them, and wipe dry with a kitchen towel.
40 grams basil
Using a pestle and mortar, crush the garlic and salt to a paste.
2 cloves garlic, sea salt
Add a few basil leaves at a time, grinding in a light, circular motion, till all the leaves have been cut to small bits and add the cheese. Mix in the banana if using.
1 tablespoon mashed banana
Stir in the oil , add the grated cheeses and mix well till fully amalgamated. Serve immediately.
If using a blender, blend the garlic and salt first, then add the leaves.
Blend in short pulses, stopping to push down the leaves every so often, till it becomes a paste.
Spoon out into a bowl/jar, and stir in the banana and cheeses, then mix in the oil.
To serve with pasta, mix in a little of the starchy pasta water to combine it well.
Fresh pesto always has the best flavour, but will keep in an airtight container for a day or two in the fridge.
Pesto will darken on exposure to air, so make sure there is a layer of oil covering the pesto before sealing and storing in the fridge/freezer to prevent oxidation.
Blend with 1 tablespoon banana for extra creaminess, but this will reduce the amount of time it can be stored in the fridge.
Pesto can also be frozen in ice cube trays, and stored in freezer bags.