Brush the sliced sweet potatoes with olive oil and rub with about 1 teaspoon of spice mix per side.
Lay potatoes on the grill and cook until grill lines form, 5-6 minutes. Flip and cook on the other side until cooked through and tender, about 5-6 more minutes. Remove from the grill and lay on a platter. Squeeze lime juice over the top and sprinkle with cilantro. Serve immediately.
*To simplify, you can also mix 2 tablespoons brown sugar, 1 teaspoon smoked paprika, 1 teaspoon chili powder, and 1 teaspoon kosher salt.