In a saucepan over medium-high heat, heat the oil. Add the onion, reduce the heat to medium-low and cook until softened and just beginning to brown, about 10 minutes. Add the ketchup, vinegar, honey, adobo sauce and salt and stir to combine. Reduce the heat to low and cook, uncovered, for 15 minutes. Remove the pan from the heat. Spoon about 1/2 cup of the sauce into a small bowl; set aside. Cover the pan to keep the remaining sauce warm.
Preheat the grill.
Season the pork chops on both sides with salt and pepper to taste and lightly brush with oil. Place the chops on the hottest part of the grill and cook until browned. Turn the pork chops and brush the browned sides with sauce from the bowl. Cook the chops until the other side is brown, then turn and transfer to a cooler part of the grill and continue to cook, basting occasionally with the sauce, until cooked through, about 8 minutes, depending on the thickness of the chops.
Serve the chops with some of the reserved warm sauce spooned over each chop.