My sister begs me to make this for family gatherings. It is sweet, savory, and uses only 4 ingredients

Once cooked, carefully transfer the pork roast to a cutting board. Let it rest for about 10 minutes, then slice or shred the meat, depending on how you want to serve it.
While the pork rests, skim any excess fat from the surface of the sauce in the slow cooker. If you want a thicker, stickier sauce, remove the lid and set the slow cooker to HIGH for 10 to 15 minutes to let the sauce reduce slightly, stirring occasionally.
Return the sliced or shredded pork to the slow cooker and toss gently in the warm honey mustard sauce, or arrange the pork on a serving platter and spoon the glossy golden sauce over the top. Serve hot with extra sauce on the side.
Variations & Tips
For a slightly different flavor without adding more ingredients, you can swap the Dijon mustard for yellow mustard for a milder, more nostalgic hot-dog-stand taste, or use a coarse grain mustard for extra texture. If you prefer a less sweet roast, reduce the honey to 1/3 cup and increase the mustard slightly. To make this more weeknight-friendly, prep the sauce the night before and store it in the fridge; in the morning, just pour it over the pork and turn on the slow cooker before work. Leftovers keep well for up to 3 to 4 days in the refrigerator and reheat nicely in a covered skillet over low heat with a splash of water. This same 4-ingredient method also works with a smaller 2 lb roast—just reduce the salt slightly and start checking for doneness about an hour earlier. If your slow cooker tends to run hot, aim for the lower end of the cook time range to keep the pork juicy instead of dry.