In a measuring cup, whisk together maple syrup, coconut aminos, rice vinegar, toasted sesame oil, and red pepper flakes until well combined. Slowly incorporate arrowroot powder to avoid clumps, stirring until the mixture is smooth and creamy. Set the sauce aside.

Heat a large skillet over medium-high heat and add a drizzle of olive oil. Once the pan is shimmering, add the ground beef, breaking it apart with a wooden spoon. Cook for about 5 minutes, stirring occasionally, until the beef is browned.

Stir in the minced garlic and grated ginger, allowing them to sauté with the beef for an additional 1-2 minutes. Stir frequently to prevent the garlic from burning.

Toss in the diced red bell pepper and shredded carrots, stirring well to incorporate with the beef. Sauté for about 3-4 minutes, until the vegetables have softened slightly but still retain some crunch.

Drizzle the prepared sauce over the beef and vegetable mixture, using a spatula to combine everything thoroughly. Let it simmer for 2-3 minutes, allowing the sauce to thicken.

Fold in the sliced green onions, stirring just until they soften. Your mixture is now ready to spoon into crisp lettuce cups.

Carefully spoon the savory filling into the leafy Boston Bibb lettuce cups, garnish with sesame seeds, and serve immediately.