Cut meat into 2" chunks.

PREP AND BROWN BEEF: Pat beef dry with paper towels and cut into 2" chunks; sprinkle with salt and pepper. Set Instant Pot (IP) on SAUTE, add 1 tablespoon oil. Add beef pieces in batches in a single layer, turning to brown on all sides. Remove browned beef to a plate and add remaining beef to IP, brown on all sides and remove to plate. Add vinegar and deglaze the IP, scraping and stirring in the browned bits from the bottom. Sprinkle in taco seasoning, stirring for 1 minute. Add half of broth and whisk to remove any lumps; then add remaining broth.

COOK AND SHRED BEEF: Add browned beef back into liquid in IP. Secure lid on IP and set vent to SEALING. Press MANUAL (it automatically sets it at HIGH PRESSURE), then press the "+" button repeatedly until 70 (minutes) is displayed. When cooking cycle is complete and machine beeps, press CANCEL or unplug IP to turn it off. Allow to naturally release.

NOTE: Although actual cooking time is 70 minutes, total time from turning on IP, building pressure, and to the end of the natural release time is approx. 2 hrs.

Use tongs to remove cooked beef to large cutting board or baking sheet (like a 13x18 half-sheet pan); shred it using two forks, removing and discarding any visible pieces of fat.

STRAIN AND DEGREASE LIQUID: Strain cooking liquid left in the IP by pouring it through a wire mesh strainer.

Degrease liquid, if desired, by (1) spooning grease layer off top, or (2) pouring liquid into a grease separator, or (3) chilling liquid in refrigerator until fat on top solidifies and can be scraped off.

REDUCE BROTH: Return strained/defatted broth to IP, set on SAUTE, and cook uncovered until beginning to thicken. Add shredded beef and toss to coat with thickened broth.

SERVING SUGGESTIONS: --a filling for tacos, burritos, fajitas, chimichangas, enchiladas or a topping for nachos --a topping for Mexican rice bowls --serve on a bun for a quick, tasty sandwich --add to chili or stew --add to grilled sandwich/panini along with melted cheese