Preheat oven to 350°F (180°C). Cut flank steak into large pieces that will fit on the bottom of a Instant Pot in 2 batches. Season with salt and pepper. Heat oil in Instant Pot over medium-high heat until shimmering. Working in batches, add steak and cook, turning, until browned, about 6 minutes per batch. Transfer steak to a plate and set aside.

Add onion and bell peppers to Instant Pot and cook, stirring and scraping up browned bits from bottom of pot, until onion and peppers are tender, about 8 minutes. Add garlic and cook for 1 minute longer; lower heat and/or add more oil at any point if ingredients threaten to burn.

Stir in tomato paste, cumin, oregano, and allspice and cook, stirring and scraping, for 1 minute.

Add white wine and bring to a simmer, scraping up any browned bits from bottom of pot. Boil until raw alcohol smell has cooked off from wine, about 2 minutes, then add canned tomatoes and stock. Return beef to pot, nestling it under the liquid among onions and peppers, along with any of its accumulated juices. Nestle bay leaves, carrot, and celery into pot. Add more stock, just enough to cover all the ingredients, if necessary.

Close Instant Pot and pressure cook for 38 minutes and depressurize

Remove bay leaves, carrot, and celery from pot and discard. Remove beef from pot and, using 2 forks, pull apart into very thin, long shreds. Return beef to pot, stirring to combine with vegetables and cooking liquid.

Stir in olives, return Instant Pot to medium heat, and simmer until juices have reduced just enough to coat the beef in a rich, saucy glaze. Season with salt and pepper. Stir in cilantro, then serve with rice and beans.