Select "Saute" function on Instant Pot. Heat oil oil in Instant Pot and add onions and garlic; saute until onions are translucent.
Rinse lentils well and drain; add to onions and garlic in pot. Add remaining ingredients and stir.
Cover and cook at high pressure for 10 minutes. Let pressure release naturally 10 minutes. Release remaining pressure.
Serve with tortillas, chopped lettuce, salsa, and fresh cilantro.