Preheat your heavy-bottomed pot over medium heat and add the olive oil.
Add the turmeric and cumin seeds (if using) to the dry pan. Toast for about 30 seconds until fragrant, watching for a warm, earthy aroma.
Stir in the chopped onion and minced garlic. Cook, stirring occasionally, until the onion becomes translucent and fragrant, about 5 minutes.
Add the diced carrots and celery. Cook for another 5-7 minutes, stirring often, until the vegetables soften slightly and start to release their natural sugars.
Pour in the vegetable broth and rinse the lentils under cold water. Bring the mixture to a gentle simmer, then cover and cook for 20-25 minutes, stirring occasionally, until the lentils are soft and breaking apart.
Check the texture; the soup should be velvety and thickened from the broken-down lentils. If it’s too thick, stir in a splash more broth to loosen it.
Add the chopped greens to the soup and cook just until wilted, about 2 minutes, stirring gently.
Remove the pot from heat and squeeze fresh lemon juice into the soup. Season with salt to taste and stir well.
Allow the soup to rest for a few minutes, letting flavors meld. Taste once more and adjust seasoning if needed.
Serve the soup warm, with a drizzle of olive oil or a sprinkle of fresh herbs if desired. Enjoy this nourishing, vibrant bowl!