Wash the watercress and remove the leaves. Set some leaves aside for garnishing. Grate the cheese. Roast almonds in a pan without fat. Take them out and let them cool down. Peel and roughly chop the garlic.
Puree the watercress, garlic, almonds, cheese and olive oil with a hand blender to a smooth sauce. Season to taste with salt and pepper.
Put the bacon in a pan, heat it up and let it crisp while turning. Take out and drain on kitchen paper. Wash and clean the tomatoes and, depending on their size, cut them in half or into slices.
Mix tomatoes and 2 tablespoons of herb sauce, season with salt and pepper. Arrange tomato salad and bacon on plates, drizzle with remaining sauce. Garnish with watercress leaves. Serve with a rustic farmhouse bread.