Ripe avocados yield to gentle pressure and are dark green to black. Halve them, remove the pit, and scoop the flesh into a bowl.
Mash the avocado with a fork to your preferred texture — chunky or smooth. Leave some lumps for character.
Stir in the juice of 1 lime, 0.5 tsp salt, half a finely diced white onion, 1 minced garlic clove, and 1 finely chopped jalapeño (seeds removed).
Fold in a small handful of chopped coriander. Taste and adjust salt and lime. Serve immediately, or press cling wrap directly onto the surface to prevent browning.