Make this several hours in advance to allow the juices to permeate the bread (pan bagna means “bathed bread”). The olive oil plays a prominent role, so be sure to use really good, fruity oil.
1 baguette, about 16 inches long
3 or 4 anchovies, optional (but excellent)
2 cloves garlic
1⁄4 teaspoon kosher salt or other coarse salt
3 tablespoons extra-virgin olive oil
1⁄2 teaspoon Dijon mustard
10 to 12 oil-cured black olives or Kalamata olives, pitted and sliced
1 small bell pepper (any color), cored and sliced into very thin rings
3 or 4 very thin slices of small red onion, separated into rings
2 medium tomatoes, thinly sliced
Freshly ground black pepper
10 to 12 medium-sized basil leaves
1 small cucumber
Cut baguette in half horizontally. Pull out some of the insides to create a somewhat hollowed-out loaf (reserve pulled-out bread for another use). With mortar and pestle, pound together anchovies, garlic and salt until smooth. Add oil and mustard; blend well with a fork. Brush the cut sides of the bread with oil mixture, using about half or a little more of the mixture. Scatter the olives over the bottom half of the bread. Arrange bell pepper over the olives; top with onion and tomato slices. Drizzle remaining oil mixture over tomatoes; grind black pepper to taste over tomatoes. Arrange basil on top of tomatoes. Cut cucumber in half lengthwise; use a spoon to scrape out and discard the seedy core. Slice cucumber halves about 1⁄8 inch thick, then arrange on top of the basil. Place top half of the bread in place; cut loaf into 2 shorter halves. Wrap each half tightly in plastic wrap; place in refrigerator. Set a baking dish on top of the sandwich halves, then pile a few heavy cans or a brick on the baking dish to weight the sandwich. Refrigerate, weighted, for at least 2 hours, or as long as 8 hours. Cut each half into two pieces before serving.
Variations: This sandwich is very versatile and adapts well to other ingredients. Try replacing the basil with watercress or arugula (or use one of these in addition to the basil). Sliced radishes add nice color and crunch; a sprinkle of capers enlivens the taste and is a nice addition if you don’t use the anchovies. For a more substantial sandwich, drain a can of oil-packed tuna and flake it over the bell pepper layer, or add a layer of sliced or crumbled hard-cooked egg (be sure to keep these versions cold until served).