Summer Crab Rolls

Ingredients

• 1/4 cup finely chopped Vidalia or other sweet onion
• 1/4 cup low-fat mayonnaise
• 2 tablespoons chopped fresh chives
• 1 tablespoon Dijon mustard
• 1 teaspoon fresh lemon juice
• 1/2 teaspoon hot pepper sauce (such as Tabasco)
• 1 pound lump crabmeat, drained and shell pieces removed
• 1 1/2 tablespoons butter, softened
• 12 (1-ounce) dinner rolls, cut in half horizontally
• 12 Boston lettuce leaves (about 1 small head)
• 6 plum tomatoes, each cut into 4 slices