Cook the lentils according to package instructions in 1 + ½ cups salted water until tender, 14 to 16 minutes, then drain, rinse with cold water, and set aside. Meanwhile, prepare the sriracha tahini sauce by whisking all ingredients in a small bowl until smooth. Set aside.
Heat the oil over medium heat in a large, deep skillet. Once the oil is shimmering, add the ground beef. Sauté, stirring occasionally and breaking into small pieces, until browned all over, 5 to 7 minutes.
Season the beef with the ginger, salt, garlic, and red pepper flakes and mix to combine. Continue cooking and pour in the coconut aminos, maple syrup, sesame oil, and sriracha. Mix to coat and cook down the sauce for 3 to 4 minutes.
Add the cooked lentils to the skillet and mix well. Simmer for an additional 2 to 3 minutes to let the flavors combine and absorb most of the liquid, then remove from heat.
Assemble the lettuce wraps by filling the lettuce leaves with a few spoonfuls of the beef and lentil mixture, evenly dispersing, and topping with the sliced carrots, green onion, and chopped cilantro. Drizzle the sriracha tahini sauce and sprinkle sesame seeds on top.
