Prep your lettuce. Gently separate the leaves, rinse, and pat dry. Keep them chilled so they stay crisp.
Make the sauce. In a small bowl, whisk soy sauce, hoisin, rice vinegar, sesame oil, chili-garlic sauce, and honey.
Taste and adjust heat or sweetness. Set aside.
Heat the pan. Add oil to a large skillet over medium-high heat. When it shimmers, add the onion and cook 2–3 minutes until softened.
Cook the aromatics. Stir in garlic and ginger for 30 seconds until fragrant.
Don’t let them brown.
Brown the turkey. Add ground turkey, breaking it up with a spoon. Cook 5–7 minutes until no longer pink. Season lightly with salt and pepper.
Add the crunch. Stir in shredded carrots, chopped water chestnuts, and half the green onions.
Cook 2 minutes to soften slightly.
Sauce it up. Pour the sauce over the turkey mixture. Stir and let it simmer 1–2 minutes. If you want it thicker, add the cornstarch slurry and simmer another minute until glossy.
Taste and finish. Adjust with more soy for salt, vinegar for brightness, or chili sauce for heat.
Remove from heat.
Assemble. Spoon the turkey mixture into lettuce cups. Top with remaining green onions, sesame seeds, cilantro, and a squeeze of lime.
Serve immediately. Enjoy as-is, or pair with steamed rice or cauliflower rice for a fuller meal.