Place the lentils in a medium pot and fill it iwth enough water to cover them by 2 inches (5 cm). Add the onion, bay leaf, and salt. Bring to a boil over high heat, reduce the heat to low, and simmer for 10 minutes, or until the lentils begin to soften but are not completely cooked. Drain.
Place the tomatoes and chipotle in a blender and purée until smooth. You should have about 1 ½ cups (354mL) of purée.
Heat the oil in a large pot over medium-low heat. Add the onion and cook for 3 to 4 minutes, until it becomes tender and translucent. Add the garlic and cook for 1 minute. Add the lentils and, using a potato masher, mash to break them up a bit, leaving one-quarter of the lentils whole.
Add the tomato purée and carrot and simmer for 3 to 4 minutes, until the purée thickens and changes to a deep red color. Add the vegetable broth, potato, cumin, oregano, salt, and pepper. Bring to a boil over high heat, reduce the heat, and simmer until the vegetables are tender, for 20 to 25 minutes. As it cools, the lentils will absorb some of the broth.
Serve with rice and warm corn tortillas. STore in an airtight container in the fridge for up to 4 days or in the freezer for up to 3 months.