To make the Romesco sauce
Wrap half a head of garlic and the tomatoes in aluminium foil. Cook them for 30 minutes in the oven at 180°C. Peel the tomatoes and the garlic and remove the skin. Use the blender to blend the tomatoes, garlic, hazelnuts, almonds, vinegar, pulp of dried red pepper and water and form a thick texture. Add salt and pepper to taste. Add the olive oil and mix constantly to yield a homogeneous texture.
Preheat the oven to 200º C. Bake the gluten-free Ciabatta bread for 15 minutes in the oven at 200° C. Grill the loin and asparagus with a little oil. Add salt and pepper to taste. Cut the Ciabatta into two, spread each half with a little Romesco sauce and arrange the asparagus and the loin on top. Heat the bread for 2 minutes in the oven and serve hot.