Set a large heavy pot or Dutch oven over medium heat and let it warm for about 1 minute.

Add the olive oil to the pot and swirl it to coat the bottom.

Put the chopped onion and chopped bell pepper into the pot. Sprinkle in a small pinch of salt and cook for 6 to 8 minutes, stirring often, until the vegetables look soft and the onion is no longer crisp.

Add the minced garlic to the pot. Stir for 30 seconds, just until it smells fragrant.

Add the chopped chipotle peppers, the tablespoon of adobo sauce, the ground cumin, and the chili powder to the pot. Stir for 30 seconds so the spices bloom in the oil.

Pour the crushed tomatoes into the pot. Stir well and cook for 2 to 3 minutes, until the tomatoes darken slightly and the mixture looks a little thicker.

Add the rinsed lentils and the vegetable broth to the pot. Stir and scrape the bottom of the pot so nothing is stuck there.

Raise the heat to high and bring the pot to a full boil.

Lower the heat to medium-low so the liquid bubbles gently. Partly cover the pot and simmer for 25 minutes, stirring every so often to make sure the lentils are not sticking.

Check a lentil by scooping one out with a spoon and biting into it carefully. When the lentils are starting to soften but still have a little firmness in the center, add the drained chickpeas to the pot.

Keep simmering the chili for 8 to 10 minutes more, partly covered, until the lentils are fully tender and the chili is thick enough to sit up on a spoon. If the pot gets thicker than you like before the lentils are tender, stir in up to 1/2 cup water.