This recipe for Romesco sauce comes courtesy of Hugo, co-owner of the adorable Gastromaquia in Madrid.
I say recipe, but really what he shared was a method and ingredients rather than exact measurements. His family comes from Tarragona in the south of Catalonia, and he emphasized to me that everyone has a different variation on this classic Spanish sauce, and his is by no means the definitive version; on the contrary, there is no definitive version.
Here is what Hugo told me: "First you roast the tomatoes and garlic. Then you fry raw Marcona almonds in olive oil. Put the almonds in while the oil is still cold and heat it slowly. When the almonds are almost fried, put the bread in and fry. Add the tomatoes and pepper paste and garlic. Then add sherry vinegar. Blend it together and salt to taste."
Here are the amounts and method I used: I roasted one head of garlic until soft. I fried 1/3 cup raw almonds (I could not find raw Marcona) in 3 tablespoons olive oil as Hugo specified. I then added a 1-inch-thick slice of torn-up white bread and fried until the bread absorbed the oil. To this I added 14 oz. of fire roasted tomatoes, the garlic, 1 large chopped roasted red pepper (I couldn't find the pepper paste) and a teaspoon of sherry vinegar. I pureed this with an immersion blender and added salt to taste. And that is all. Simple and beautiful.
It is traditional, he told me, to dip charred onions into the sauce, and so I grilled some spring onions to go with my Romesco. I also enjoyed this on grilled flank steak and with some broccolini. Really, though, it's hard to think of any vegetable or protein that wouldn't work with this nutty, tangy sauce.