Start the base: Set a large Dutch oven or soup pot on the stove over medium heat. Add the olive oil and let it heat until it looks loose and glossy, about 30 seconds.

Add the chopped onion and sliced fennel to the pot. Sprinkle in the 1 teaspoon kosher salt and 1/2 teaspoon black pepper.

Cook the onion and fennel, stirring every minute or two, until both are soft and the fennel looks slightly translucent, 8 to 10 minutes.

Add the sliced garlic and tomato paste to the pot. Stir for 1 minute, until the garlic smells fragrant and the tomato paste darkens a shade.

Add the rinsed lentils to the pot. Stir for about 30 seconds so the lentils are coated with the tomato paste and oil.

Pour the vegetable broth and 1 cup water into the pot. Scrape the bottom of the pot with a wooden spoon to loosen any bits stuck there.

Simmer the lentils: Raise the heat to high and bring the liquid to a boil.

Lower the heat so the stew bubbles gently. Cover the pot partway with a lid.

Simmer until the lentils are tender but still holding their shape, 22 to 28 minutes. Stir once or twice during that time, and add a splash of water if the stew starts to look too thick before the lentils are ready.

Stir the drained chickpeas into the pot. Simmer uncovered for 5 minutes so the chickpeas heat through and the broth comes back to a steady simmer.

Add the shrimp: Put the shrimp into the pot. Stir gently so the shrimp are mostly covered by the hot broth.

Cook at a gentle simmer for 3 to 5 minutes, until the shrimp are pink, opaque, and just curled. Avoid a hard boil here, which can make the shrimp tough.