, peeled and sliced, about 1 1/4 cups
2 1/3 cups
, thinly sliced
MELT butter in a large saucepan over medium-high. Add leek and artichokes. Cook until leek is soft, 3 to 4 min. Add potato, broth and wine. Boil, then reduce heat to medium-low. Stir in tarragon. Simmer, covered, for 30 min. Stir in salt. Season with fresh pepper. Purée in a blender until smooth. Cool, then refrigerate until cold, 2 to 3 hours. Stir in cream just before serving.
HEAT a frying pan over medium-high. Toss onion with oil, then arrange in 1 layer in very hot pan. Cook until onion is charred, 2 to 3 min per side. Garnish soup with onion, tapenade and tomato.