Start by heating a large heavy-bottomed pot over medium heat and add the olive oil. Once shimmering, add the diced onion and sauté until translucent and fragrant, about 5 minutes.
Add the minced garlic, ground turmeric, and cumin to the pot. Cook, stirring constantly, until the spices release their warm aroma, about 1 minute.
Stir in the diced carrots and cook for another 3-4 minutes, allowing them to soften slightly and absorb the flavors.
Pour in the vegetable broth and bring the mixture to a gentle boil. Add the rinsed red lentils, stir well, then reduce the heat to low and cover partially.
Simmer the soup for 20-25 minutes, stirring occasionally, until the lentils are melting into the broth and the soup turns a vibrant golden color.
Add the chopped spinach in the last 3 minutes of cooking. Stir until wilted and vibrant green, then taste and season with salt and pepper as needed.
If desired, stir in the coconut milk for added creaminess, allowing it to warm through for 2 minutes.
Turn off the heat and let the soup rest for 5 minutes, allowing the flavors to meld beautifully.
Serve the soup hot, garnished with a squeeze of lemon or a drizzle of extra olive oil if desired, and enjoy its comforting warmth.
