How to Make It
Put the ancho chiles in a small heatproof bowl. Add the boiling water and let stand until the chiles are softened, about 15 minutes.
Meanwhile, heat 2 tablespoons of the olive oil in a small skillet. Add the bread cubes and cook over moderately high heat, stirring occasionally, until well browned, about 5 minutes. Using a slotted spoon, transfer the toasted bread cubes to a plate and let cool.
Drain the ancho chiles, reserving 1/2 cup of the soaking liquid. Using a sharp paring knife, slit the chiles and remove the seeds. Transfer the chiles to a food processor. Add the reserved chile-soaking liquid and process until pureed. Strain the chile puree through a fine sieve set over a bowl.
In the food processor, combine the garlic with the almonds, coriander and cumin. Add the bread cubes and process until finely chopped. Add the ancho chile puree, tomatoes and piquillo peppers and process until smooth. With the machine on, slowly add the remaining 1 cup of extra-virgin olive oil and process until smooth. Season the romesco sauce with salt and scrape into a bowl.