1 pork tenderloin (about 1 pound), cut into 1/4-inch-thick slices, then cut crosswise into 1 1/2-inch pieces
1/4 cup reduced-sodium soy sauce
1 tablespoon unseasoned rice vinegar
1 tablespoon hoisin sauce, plus more for serving
1/4 cup vegetable oil
3 cloves garlic, minced
1 tablespoon minced fresh ginger
1 bunch scallions, cut into 2-inch pieces
8 ounces shiitake-mushroom caps, thinly sliced
1 bag (12 ounces) coleslaw
8 flour tortillas, warmed

In a bowl, toss pork with 2 tablespoons soy sauce; let stand 10 minutes. Whisk together remaining 2 tablespoons soy sauce, vinegar, hoisin, and 2 tablespoons water.

Heat a large cast-iron or nonstick skillet over medium-high. Swirl in 1 tablespoon oil; add half of pork and cook until browned on one side, about 2 minutes. Flip and cook 1 to 2 minutes more; transfer to a plate. Repeat with remaining pork.

Swirl in remaining 3 tablespoons oil. Add garlic, ginger, and scallions; cook, stirring, 30 seconds. Add shiitakes; cook 2 minutes. Add coleslaw; cook, stirring, until vegetables are tender, 2 minutes.

Add soy mixture and return pork to skillet; cook, stirring, until combined, about 1 minute. Serve in tortillas with more hoisin.