Set a large heavy pot or Dutch oven on the stove over medium heat.

Add the olive oil to the pot and let it heat for about 30 seconds.

Add the chopped onion and diced carrots to the pot. Cook, stirring now and then, for 5 minutes, until the onion starts to soften.

Add the chopped garlic and berbere spice blend to the pot. Stir for 30 seconds, just until the garlic smells fragrant.

Add the tomato paste to the pot. Stir it into the vegetables for 1 minute, until it darkens slightly and coats the bottom of the pot.

Put the sweet potato cubes into the pot. Stir well so the pieces get coated with the spiced tomato mixture.

Add the rinsed lentils to the pot and stir once more.

Pour the vegetable broth into the pot and scrape the bottom with a wooden spoon to loosen any bits stuck there.

Raise the heat to medium-high and bring the broth to a full boil.

Lower the heat to medium-low so the liquid bubbles gently. Cover the pot partway with a lid.

Simmer the stew for 20 minutes, stirring once or twice, until the lentils have started to soften but are not fully tender yet.