Prep the lettuce and toppings: Rinse the lettuce leaves and pat them dry. Slice green onions, shred the carrot, and chop any herbs or nuts you want to add.
Set aside.
Make the sauce: In a small bowl, whisk soy sauce, hoisin, rice vinegar, sriracha, sesame oil, and brown sugar. Taste and adjust salt, heat, or sweetness as needed.
Cook the beef: Heat the oil in a large skillet over medium-high. Add the ground beef and break it up with a spatula.
Cook until browned with crispy edges, about 5–7 minutes.
Add aromatics: Reduce heat to medium. Stir in garlic and ginger. Cook 30–60 seconds until fragrant, stirring so nothing burns.
Sauce it up: Pour in the sauce and add half the green onions.
Stir and let it simmer 1–2 minutes until the liquid reduces slightly and coats the beef.
Taste and finish: Adjust seasoning. If you want more brightness, squeeze in a little lime. If you like heat, add more sriracha.
Assemble: Fill lettuce leaves with a spoonful of beef.
Top with shredded carrot, remaining green onions, cilantro, nuts, cucumber, and sesame seeds. Serve with lime wedges.