Start by heating olive oil in a large pot over medium-high heat. Add chopped onions and cook until they turn translucent, typically taking about 3-5 minutes.
Mix in minced garlic, chopped carrots, and celery to the pot, cooking for an additional 2-3 minutes until they start to soften.
Combine green lentils, cumin, coriander, kosher salt, and black pepper with the vegetables. Cook for about 5 minutes to lightly toast the lentils, enhancing their flavor.
Pour in the vegetable broth and bring the mixture to a boil. Then, lower the heat and let it simmer for about 30 minutes. The lentils should be tender, and the broth slightly thickened.
Fold in the kale and continue to simmer for an additional 2 minutes, or until the kale has wilted and is tender.
Once the soup is done, remove it from heat. It's now ready to ladle into bowls and serve warm.