In a small bowl, thoroughly mix sauce ingredients.
Place lettuce in a large bowl.
Bring a skillet sprayed with nonstick spray to medium-high heat. Add beef, onion, and seasonings. Cook and crumble for about 5 minutes, until beef is fully cooked and onions have softened.
Remove skillet from heat. Add mustard, and stir until well mixed.
Add beef mixture to the large bowl. Top with remaining ingredients.
Top with sauce, or serve it on the side.
Recipe by 5* trending recipes with videos at https://food.theffeed.com/2018/01/28/mac-attack-burger-bowl/