1. For the Sauce, mix all ingredients in small bowl. Cover. Refrigerate until ready to serve.
2. For the Crepes, mix flour, cornstarch and sea salt in large bowl with wire whisk. Gradually add water, whisking until batter is very smooth. Whisk in sesame oil. (Batter will be thin.) Let stand while preparing filling.
3. For the Filling, mix seasonings in small bowl. Form ground beef into large patty. Sprinkle both sides with seasoning mixture.
4. Heat oil in medium cast iron skillet on medium-high heat until shimmering. Add onion; cook and stir 1 to 2 minutes. Add beef patty; cook 2 to 3 minutes or until seared. Turn patty over then top with cheese slices. Using a metal or wooden spatula, chop the cheese into the patty until well blended. Cook 2 to 3 minutes or until beef is cooked through. Keep warm.
5. To cook the crepes, brush about 1/2 teaspoon of the oil in 12-inch nonstick skillet on medium-low heat. Pour about 1/3 cup of the batter into skillet, tilting to evenly cover bottom of skillet. Cook 2 to 3 minutes or until bottom of crepe begins to brown.
6. Lightly beat 1 egg in small bowl then pour over crepe in pan in even layer to cover crepe. Continue to cook 1 to 2 minutes or until egg is just set. Using a flexible spatula, carefully turn crepe over. Cook 2 to 3 minutes or until crepe is lightly browned and crispy. Place crepe, egg side down, on cutting board. Repeat with remaining batter and eggs.
7. To assemble, spoon 1/4 each of the Filling, fried onions and lettuce, and 2 tablespoons of the Sauce down the center of the non-egg side of each crepe. Fold or roll crepe to enclose filling. Serve immediately.
Test Kitchen Tips:
Crepes can be made ahead of time. Store crepes between layers of waxed paper on a large plate. Cover with plastic wrap and refrigerate up to 2 days. Reheat crepes in a hot, oiled skillet, turning to crisp both sides.
To take your crepe on-the-go, cut filled crepe in half then wrap each half in waxed paper or foil.