Set pot to Saute and wait for it to say Hot. Add the oil and swirl to coat the bottom. When the oil is hot, add the onions, garlic, ginger, celery and sambal. Sauté, stirring occasionally, until the onions are soft, about 2 minutes.
Add the beef and pork and sauté, breaking up the meat until crumbly. You don't need to cook it through.
Add lime juice and diced tomatoes. and season with salt and pepper. Add the hoisin sauce right on top and don't stir that in. Just leave it. Press Cancel to stop the Sauté mode.
There should be enough liquid from the tomatoes, but you will still need to add 1/4 cup of water around the edge of the meat. Press Pressure Cook and set the time for 5 min and do a 10 min NPR.
Carefully open pot and stir the contents. If the mixture is too thin, you can press Sauté to reduce the liquid. It just depends on how much liquid the meat had in it before cooking.
Toast the buns and place a bottom half on each individual serving plate. Top generously with the meat mixture. Top with the lettuce or greens and the bun tops. Serve with the chips and limes.