Add orange juice, lime juice, olive oil, garlic, salt, oregano, cumin, sugar, and pepper to a food processor or blender and blend until smooth.
Add roast to a large bowl and pierce all over with a fork. Carefully pour the marinade over the pork. Cover and refrigerate for at least 2 hours.
Add vegetable oil to the instant pot and select the saute function. Saute meat in hot oil on both sides, browning.
Pour marinade and meat into pot and cover. Seal the lid and close the pressure release valve. Set to manual, high pressure for 60 minutes. When cooking is complete, let pressure release naturally for 20 minutes.
Open, slice or shred and serve with sauce from the pot over each serving.
Notes
Without Marinade Option
If you did not want to marinate you can either coat the outside of the meat with the seasonings before you sear and just pour the orange juice, lime juice and olive oil into the pot after sauteeing the meat.If you only want to use broth you would use 1 cup chicken or beef broth with the meat into the pot after sauteeing. You do need a cup of liquid to steam to tender properly.