Cut baguette in half along its midsection
Drizzle half of olive oil on each half of the bread, covering evenly
Spread the tuna fish over the bottom half of the bread
Spread capers and olives evenly over the tuna
Cover tuna and olives with the salad greens
Stack tomatoes, onions, cucumbers and pequillo peppers on top of the lettuce
Salt and Pepper to taste
Cover with the top half of the bread and firmly press the sandwich together.
Wrap sandwich tightly in a layer of plastic wrap, and then again with foil
Place the sandwich on a cutting board and cover with another cutting board
Place weights on the top cutting board (books, heavy cans, a small child) and let sit for 30-60 minutes to press sandwich together
Refrigerate until ready to leave for your picnic!