For a mild garlic flavor, before cooking, cut a large garlic clove into 12 slivers, pierce 12 holes all over the pork with the tip of a knife, and insert a garlic sliver into each hole. To give your sandwich a spicier kick, top with pickled sliced jalapeños before serving. Fill up your plate with coleslaw mix tossed with lime vinaigrette and chopped fresh cilantro, and offer crisp tortilla chips and tomato salsa alongside.
- Rub the pork roast all over with the chili powder and salt. Heat the oil in a large skillet over medium-high heat. Add the pork and cook, turning occasionally, until browned, about 5 minutes.
- Transfer to a 3 1/2- to 5-quart slow cooker. Add 1/4 cup water and cover. Cook on LOW until the pork is fork-tender, 5 1/2 to 6 hours.
- Transfer pork to a cutting board and let stand 10 minutes. Discard liquid in crockery insert. Slice pork crosswise into 16 thin slices, discarding string.
- For each serving, place 2 pork slices in a roll. Top with about 3 tablespoons guacamole and 2 tomato slices. Cut in half crosswise and serve warm.
- *Tip: If you desire to tie the roast, cotton kitchen twine (also called butcher's twine) is handy to have on hand for a number of chores, especially tying roasts to help them keep their shape during cooking. If you don't have it, use unwaxed and unflavored dental floss.