For a smokier flavor, add 1 teaspoon smoked paprika or a few drops of liquid smoke to the sauce mixture before pouring it over the ribs. If you prefer your ribs less sweet, reduce the brown sugar to 2 tablespoons and use a tangy, vinegar-forward barbecue sauce. For a bit of heat, stir 1/2 teaspoon crushed red pepper flakes or a teaspoon of hot sauce into the sauce mixture. You can also use country-style pork ribs instead of a full rack; just arrange them in a single snug layer at the bottom of the slow cooker and proceed with the same timing. If you want to separate the fat after cooking, pour the cooking juices into a heatproof measuring cup, let the fat rise to the top, skim it off with a spoon, and then drizzle the defatted juices over the ribs. Leftover ribs reheat well: cool completely, refrigerate in their sauce up to 3 days, then rewarm gently in a covered dish at 300°F until heated through, adding a spoonful of water if needed to keep them moist.