Mix together olive oil, lime juice, smoked paprika, cumin, and chili powder in a bowl. Pat chicken thighs dry with paper towels and toss them in the marinade, making sure every piece gets coated. Let them sit for at least 10 minutes while you prep everything else—don't panic if you only have 5 minutes, they'll still taste amazing.
Slice bell peppers into thick strips (about 1/2-inch wide) and cut red onions into thick rings. Toss these veggies in the remaining marinade or brush them with a little extra olive oil and sprinkle with salt and pepper. Having everything prepped before you start grilling saves you from that chaotic moment when everything's cooking at once.
Heat your grill to medium-high heat (around 400°F). You'll know it's ready when you can hold your hand above the grates for only 2-3 seconds before it gets too hot. My grill always has one hot side and one cooler side, which works perfectly for this.
Grill the chicken thighs for 6-7 minutes per side until you see those gorgeous char marks and the internal temperature hits 165°F. They'll sound amazing when they hit the grill—that's when you know you're doing it right. Don't flip them constantly or you'll lose those crispy edges.
Move the cooked chicken to a cooler part of the grill or a clean plate while you handle the veggies. Lay peppers and onions directly on the grates and grill for 4-5 minutes per side until they're tender with some blackened spots. This is where the magic happens—those charred edges are what everyone's gonna rave about.
Slice your grilled chicken into strips once everything comes off the grill. Arrange the chicken and vegetables on a large platter or wooden cutting board so guests can see everything at once. The presentation matters here because it makes people actually want to try building their own fajitas.
Set up your fajita bar with warm tortillas on one side and all your toppings in separate bowls: cheese, guacamole, salsa, and sour cream. Let everyone build their own plate—it's honestly the best part because nobody complains about what they got.
