Apricots add summery sweetness, with a hint of tartness, to these kebabs.
Heat grill to medium; lightly oil grates. Soak four 12-inch wooden skewers in a shallow dish of water for 15 minutes (or use metal ones).
Make basting sauce: In a small saucepan, heat jam, cayenne, and 1 tablespoon water over medium-low until jam is liquefied; season with salt and pepper.
Onto each skewer, alternately thread 5 pieces of pork with 8 of apricot and 4 of onion, beginning and ending with pork. Grill kebabs, turning occasionally and brushing with basting sauce, until pork is cooked through and apricots begin to char, 12 to 14 minutes.