Cut the baguette in half lengthwise and scoop out some of the bread to create a shell. Set crumbs aside.

In a large bowl, combine tomatoes, scallions, bell pepper, tuna, capers (if using), and reserved bread crumbs.

In a small bowl, whisk together dressing ingredients. Drizzle over tuna mixture and toss to mix thoroughly. Mound the mixture into the bottom half of the bread, packing down firmly. Top with other half of the bread. Press bread halves together and tightly wrap in plastic wrap or aluminum foil. Refrigerate for at least several hours or overnight.

Transport the bread, still wrapped, to the picnic site. Transfer to a slicing board and cut into 6 portions.

This recipe yields 6 servings.

Exchanges Per Serving: 1 Low Lean Protein, 3 Carbohydrate (2 1/2 Bread/Starch, 1 Vegetable), 1 Fat.

Nutrition Facts: 307 calories (21% calories from fat), 15 g protein, 7 g fat (1.2 g saturated fat), 46 g carbohydrates, 4 g dietary fiber, 89 mg cholesterol,584 mg sodium.