Caesar salad tostadas with white anchovies and white bean puree

Roast a couple of serrano chilies and some garlic, so the garlic does not taste raw.

In a food processor, puree 1 1/2 cups of white beans with about two-thirds of the roasted garlic and a couple tablespoons of olive oil; taste, add salt and pulse it in.

Finely chop the remaining roasted garlic, one serrano and three anchovies with a rocking chop, then mash with the side of the knife into a coarse puree; scrape into a bowl set on a damp towel.

Add an egg yolk, Worcestershire, lemon juice and a tablespoon of Dijon mustard and whisk; the oil from the anchovies starts the emulsion.

Whisk in 3/4 cup olive oil in a thin, steady stream, slowly.

Taste and season with salt and about 1/2 teaspoon of ground pepper, keeping the dressing slightly salty; add a little Parmesan.

Trim the little gem lettuce and cut into ribbons; dress lightly, adding dressing around the edge of the bowl, turn with tongs, taste and add a little more.

Smear white bean puree over each tostada, lay about three anchovies on each, pile on the salad, grate Parmesan and lemon zest over, and sprinkle with chopped roasted serrano.