To serve 4: 1 endive, finely chopped ½ kg green olives, stoned 1 small onion, chopped 1 garlic clove, finely chopped 1 tomato, chopped 1 tsp fresh tarragon, finely chopped 1 hard-boiled egg 3 tbsp olive oil 2 tbsp white wine vinegar 100 g tuna fish in olive oil,
