Cut flank steak in half across the grain. Mix salt, black pepper, and cayenne. Season both sides generously with the salt mixture.

Heat olive oil in a pot over high heat. Add steaks and cook until outsides are well browned, 4 to 5 minutes per side. Remove steaks to a plate.

Reduce heat to medium. Add red onion, garlic, and more of the salt seasoning. Cook and stir until starting to soften, 3 to 5 minutes. Stir in cumin, paprika, oregano, cayenne pepper, cloves, and allspice. Cook and stir for 1 minute. Pour in white wine, scraping up the browned bits from the bottom of the pot. Stir in tomato sauce and chicken broth.

Return beef and accumulated juices to the pot. Season with salt and add bay leaves. Reduce heat to low, cover, and simmer until beef is almost fork-tender, not falling apart, about 2 hours.

Remove pot from heat and let stew cool to room temperature, at least 45 minutes. Refrigerate, 8 hours to overnight, for best results.

Remove beef to a plate and set stew over medium heat. Tear beef along the grain into 1/8- to 1/4-inch-wide shreds; place back in the stew. Add bell peppers, poblanos, smoked paprika, capers, olives, and sugar. Stir together and reduce heat to medium. Simmer until peppers are soft and meat is tender, 15 to 20 minutes. Turn off heat, remove bay leaves, and stir in cilantro.