Bring a pan of salted water to the boil, add the peas and blanch them for 3 minutes.
Drain, then add the peas to a blender with the olive oil and the lavender or mint (if using) and blitz. Add more oil or water if needed. Blend for 2–3 minutes until smooth and thick.
If you want a silky finish use a fine sieve/fine-mesh strainer and push the purée thr