Brown the halloumi: Set a Dutch oven or heavy soup pot over medium heat. Add 1 tablespoon olive oil and let it warm for about 1 minute.

Put the halloumi into the pot in a single layer. Cook for 2 to 3 minutes on the first side, until the bottoms are golden brown.

Turn the halloumi pieces and cook for 2 minutes on the second side, until the edges look browned and crisp.

Transfer the browned halloumi to a plate. Leave any oil and browned bits in the pot.

Build the stew: Add the onion, carrots, and celery to the same pot. Cook over medium heat for 6 to 8 minutes, stirring every minute or so, until the vegetables soften and the onion looks glossy.

Add the garlic, cumin, and smoked paprika to the pot. Stir for 30 seconds, just until the spices smell warm and the garlic is fragrant.

Add the tomato paste to the pot. Stir it into the vegetables and cook for 1 minute, until it darkens a little.

Add the lentils to the pot. Stir for about 30 seconds so the lentils are coated in the tomato mixture.

Pour the vegetable broth into the pot. Use a wooden spoon to scrape the bottom so the browned bits loosen into the liquid.

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

Lower the heat so the stew simmers gently, then partly cover the pot. Cook for 20 minutes, stirring once or twice, until the lentils are starting to soften.

Add the chickpeas to the pot. Keep the stew at a gentle simmer for 10 to 15 minutes more, until the lentils are tender but still holding their shape.