To prepare dressing, remove white papery skin from garlic heads (do not peel or separate the cloves). Wrap each head separately in foil.
Bake at 400 for 1 hour; cool.
Cut crosswise, and squeeze to extract garlic pulp to measure 3 tablespoons. Discard skins.
Place garlic, mayonnaise, mustard, paste, and black pepper in a food processor; process until smooth. With food processor on, slowly pour vinegar and oil through food chute; process until well-blended.
Preheat broiler.
To prepare salad, cut bell peppers in half lengthwise; discard seeds and membranes.
Place halves, skin sides up, on a foil-lined baking sheet; flatten with hand. Broil 15 minutes or until blackened.
Place in a zip-top plastic bag; seal.
Let stand 15 minutes. Peel; cut into 1-inch strips.
Combine dressing, lettuce, 2 tablespoons cheese, and rye bread cubes in a large bowl, tossing gently to coat. Divide salad among 8 salad plates. Arrange bell pepper strips on top of salads.