Soak the skewers: If using wooden skewers, soak in water for 20–30 minutes to prevent burning.
Make the marinade: In a bowl, whisk 1/3 cup maple syrup, 1/2 cup BBQ sauce, 1–2 minced chipotle peppers plus 1 teaspoon adobo sauce, zest and juice of 1 lime, 2 minced garlic cloves, 1 teaspoon smoked paprika, 1/2 teaspoon cumin, 1 tablespoon olive oil, 1 teaspoon salt, and 1/2 teaspoon pepper.
Prep the chicken: Cut chicken thighs into 1.25–1.5-inch chunks. Pat dry for better browning.
Marinate: Toss chicken in the marinade.
Reserve 1/4 cup marinade separately for basting. Cover and chill 30 minutes (up to 8 hours for deeper flavor).
Preheat the grill: Heat a grill or grill pan to medium-high. Oil the grates to reduce sticking.
Assemble skewers: Thread chicken onto skewers, alternating with chunks of red onion or bell pepper if using.
Don’t pack too tightly.
Grill: Cook 8–12 minutes total, turning every 2–3 minutes. Brush with reserved marinade during the last few minutes to glaze.
Check doneness: Look for light char and an internal temp of 165°F (74°C). Remove and rest 3–5 minutes.
Finish and serve: Garnish with chopped cilantro or green onion.
Squeeze extra lime over the top. Serve with rice, grilled corn, slaw, or warm tortillas.