Combine garlic, bread crumbs, vinegar and olive oil in a blender. Pulse until garlic is coarsely chopped. Add tomatoes, cucumbers, thyme and parsley. Pulse or blend until mixture forms a chunky soup. Transfer to a large bowl. Stir in 2 cups ice-cold water and season with Tabasco, salt and pepper.
Cover and refrigerate until thoroughly chilled, at least 2 hours. Serve cold, garnished with croutons, if desired.