Huevos con sesos

Carefully clean the beef brains, removing any visible membranes and blood vessels. Place the cleaned beef brains in a pot with enough water to cover them, add a pinch of salt, and bring to a gentle simmer. Cook for 10-15 minutes until firm. Drain and let cool, then dice into small, bite-sized pieces.

Rehydrate the guajillo chiles by removing stems and seeds, then soaking them in hot water for 15-20 minutes until softened. Blend the softened guajillo chiles with a small amount of their soaking water until a smooth puree is formed. Strain the guajillo chile puree through a fine-mesh sieve to remove any skin fragments, reserving the smooth sauce.

Finely dice the white onion and mince the garlic cloves. Finely dice the serrano chile.