Set the Instant Pot to saute mode and add the diced onion. Cook for 3 minutes until it softens.
Add the minced garlic and grated ginger. Stir for 1 minute until fragrant.
Stir in the berbere spice and salt. Cook for 30 seconds to toast the spices.
Add the rinsed lentils, sliced carrots, diced tomatoes with their juice, and vegetable broth. Stir to combine.
Cancel saute mode. Secure the lid and set the valve to sealing. Cook on manual high pressure for 15 minutes.
Allow a natural pressure release for 10 minutes, then quick release any remaining pressure.
Open the lid and stir the stew. Serve in bowls topped with chopped cilantro and a squeeze of lemon.