Salsa mexicana

Cut the sides off each tomato, cut out the tough stem end, slice into strips and cut across into small dice; scoop into a bowl.

Cut about a third of a large white onion into strips and then across into small pieces.

Rinse the chopped onion in a strainer under cold running water to remove the sulfurous compounds; tap the strainer dry and add to the tomatoes.

Cut the serrano lengthwise and across, keeping the seed pod and veins for heat, then rock-chop to a mince; add to the bowl.

Tuck the cilantro leaves under and slice thinly across stems and leaves; discard the remaining stems and add to the bowl.

Season with a scant teaspoon of salt and a good squeeze of fresh lime juice.

Let sit about an hour so the onion softens and the flavours come together; taste and re-season salt and lime.