While the peppers are grilling, halve the avocados and scoop
out the flesh. Dice into 1–2cm (½–¾ inch) pieces, putting them
into a bowl as you go. Add most of the basil (reserving a little
to garnish), drizzle in the balsamic vinegar and season with salt
and pepper. Stir to mix, roughly crushing the avocado as you go.
Set a heavy-based frying pan on the hob or barbecue. Add about
3–5mm (1/8–¼ inch) of oil and leave to heat up until shimmering