For the crostini with olive paste, dab the anchovy fillets dry and chop them. Pit the olives, cut them into small pieces and pound them to a paste with the anchovies, capers and garlic in a mortar (or with a blender). Mix in a little olive oil until a creamy paste is formed.
Season with lemon juice, salt and pepper. Toast the bread in the preheated oven at 200°C (top heat), spread the olive paste on it and toast it again lightly. Serve quickly so that the crostini remain crispy.