Step 1

Prepare grill for direct cooking over medium heat (about 400 degrees F). Grill pepper over direct medium heat, with lid closed as much as possible, until black and blistered all over, about 15 minutes, turning occasionally. Place pepper in bowl. Cover with plastic; let steam 10 minutes. Peel skin form pepper; discard. Remove stem and seeds. Roughly chop pepper.

Step 2

In skillet over medium heat, toast almonds 3 to 5 minutes, stirring often. In food processor or blender, combine pepper, almonds, and remaining spread ingredients. Process or blend until completely smooth.

Step 3

Brush onion slices lightly on both sides with olive oil. Grill over direct medium heat, with lid closed as much as possible, until well marked and caramelized, about 10 minutes, turning once. Move onions to a cutting board to cool. Chop about half of the onions very finely (about 1/2 cup). Set remaining slices aside for serving.

Step 4

Increase grill temperature to high (about 500 degrees F), or add additional coals and heat until high heat is reached.

Step 5

In large bowl gently mix the ground chuck, the chopped onions, salt, and pepper. Shape into 4 patties of equal size and thickness, about 3/4 inch thick. With your fingertips or thumb, make a shallow indentation about 1 inch wide in the center of each patty so centers are about 1/2 inch thick.

Step 6

Grill patties over direct high heat, with lid closed as much as possible, until cooked to medium, 8 to 10 minutes, turning once or until the patties release easily from the grate without sticking. During the last minute of grilling, grill buns, cut sides down, for about 10 seconds.

Step 7

Spread some of the spread on the grilled sides of each bun. Top with a burger, lettuce leaves, and grilled onions. Makes 4 servings.