Step 1

In a small bowl, thoroughly mix sauce ingredients.

Step 2

Bring a large skillet sprayed with nonstick spray to medium-high heat. Add beef, onion, and seasonings. Cook, stir, and crumble until beef is fully cooked and onion has softened, 5 - 7 minutes.

Step 3

Remove skillet from heat. Add mustard, and mix well.

Step 4

Spread lettuce leaves with sauce and fill with beef mixture, about 1/4 cup each. Top with cheese, chopped pickles, and sesame seeds.