Heat the oil in a pan. Briefly sauté the onion and peas. Pour in the water and Martini, reduce almost completely. Add the pesto and lime juice, puree the peas, season with salt, leave to cool.
Spread the pea hummus over the lettuce leaves. Top with the avocado, add the feta. Slice off the top and bottom of the lemon, then peel all round the fruit down to the flesh. Using a sharp knife, cut out the segments between the white membranes. Top with the pistachios, lemon segments and coriander.