Cut bread into cubes. Heat 4 tablespoons of oil in a frying pan and fry the bread cubes while turning them into croutons. Season with salt and pepper. Peel garlic and onion and cut into fine cubes.
Heat 1 tablespoon of oil and sauté the onion and garlic while stirring until transparent. Add tomatoes and puree finely with a hand blender. Wash basil, shake dry, pluck the leaves from the stalks and chop, except for a little to garnish.
Season soup with salt, sugar and Tabasco. Stir in basil, except for a little bit for sprinkling. Stir sour cream and milk until smooth. Arrange soup in cups. Garnish with sour cream and basil. Sprinkle with croutons.