Sprinkle beef all over with salt and pepper. In a 6 or 8-quart Instant Pot heat oil using the saute setting then brown pieces on all sides. (Alternatively, in a large skillet brown beef over medium high heat). Remove beef to a plate.
Add broth, tomato sauce, and chili powder to Instant Pot, then place beef back in. Place lid on Instant Pot, and seal. Make sure steam valve is set on "sealing". Cook using manual setting (high pressure) for 1 hour.
Let pressure release naturally for 10 minutes, then use tongs to open steam valve and release pressure completely. Use 2 large forks to shred beef and toss with sauce to coat. Serve the beef with the tortillas, and with lettuce, pico de gallo, shredded cheese, cilantro, and lime wedges, if desired.
This nutritional information refers to each serving of the entire recipe and not just the products used as ingredients.