Press Sauté—normal/medium on the Instant Pot and heat the lard. Add half of the pork in a single layer and cook, stirring occasionally, for about 5 minutes, until lightly browned. Season with 1 1/2 tsp of the salt and 3/4 tsp of the pepper, then, using a slotted spoon, transfer the pork to a plate. Add the remaining pork, the onion, garlic, and cumin and cook, stirring occasionally, for about 2 minutes, until lightly browned. Season with the remaining 1 1/4 tsp salt and the remaining 3/4 tsp pepper. Add the flour and cook, stirring frequently, for about 2 minutes, until the flour begins to brown. Add the reserved pork, the broth, tomatoes, and potatoes (if using) and scrape up any browned bits on the bottom of the pot. Press Cancel.