Heat the olive oil in a large heavy-bottomed pot over medium heat until it starts to shimmer and crackle gently.
Add the finely chopped onion and cook slowly, stirring occasionally, until it becomes translucent and fragrant, about 5 minutes. You should hear a gentle sizzle and see the onion turn a light golden color.
Toss in the crushed garlic and cook for about 30 seconds, stirring constantly, until fragrant. Be careful not to burn it—the garlic should smell sweet and pungent.
Add the diced carrots and thinly sliced celery to the pot. Stir well and cook for another 5-7 minutes, until the vegetables soften slightly and begin to release their aroma. You’ll notice the vegetables turning tender and the mixture smelling earthy and warm.
Sprinkle in the ground cumin, smoked paprika, and chili flakes if using. Toast the spices with the vegetables for about 30 seconds until fragrant, stirring constantly to prevent burning and to deepen their aroma.
Pour in the vegetable broth and add the rinsed lentils. Stir to combine, then bring the mixture to a gentle boil over high heat. You’ll hear a steady bubbling as the stew begins to cook.
Reduce the heat to low, cover the pot partially, and let the stew simmer gently for about 25-30 minutes. Stir occasionally and watch as the lentils become tender and the vegetables soften further, filling your kitchen with a fragrant, smoky aroma.
Uncover the pot, taste the stew, and season with salt and pepper to your liking. If you prefer a thicker consistency, let it simmer uncovered for a few more minutes to reduce and intensify the flavors.
Remove the stew from heat and let it sit for 5 minutes to settle and allow flavors to meld. The lentils should be soft but still hold their shape, and the broth will be thick and inviting.
Spoon the hearty stew into bowls, garnish with fresh herbs if desired, and enjoy the warm, smoky, comforting flavors in every spoonful.
