Step by step
Tear the basil leaves by hand and add to the mortar, then pound with a little oil so that it doesn’t blacken
Tips
The pesto can certainly be made in advance: but because of its tendency to oxidize, you have to make sure you cover it with a little extra virgin olive oil.
Trivia
The pesto is made using a mortar and pestle - hence the name - generally in this order: first pound the garlic together with the pine nuts, then add the basil leaves.