Grind almonds, 2 garlic cloves, and salt to a fine consistency in a food processor or blender. Soak stale bread in one cup ice water, and squeeze to extract moisture. Add bread to processor. With processor running, add 6 tb oil and one cup ice water slowly in a steady stream. Add vinegars, and mix on high speed for 2 minutes. Add one cup ice water and mix 2 more minutes. Place in a bowl, add remaining ice water and mix well. Adjust seasonings with salt and vinegar. Chill for up to 6 hours.
Heat butter and remaining one tablespoon olive oil in a skillet. Crush remaining garlic clove and add to pan with bread cubes, tossing to coat with butter and oil. Cook over very low heat, stirring occassionally, 20-30 minutes, or until cubes are golden.
Serve soup ice cold, garnished with croutons and grapes.