Heat the oil in a large pot or Dutch oven over medium heat, add the onions & carrots and sauté until soft, 5 - 6 minutes, stirring.
Add the chopped garlic, turmeric and cumin and continue cooking for 2 - 3 minutes more.
Stir in the lentils, add the broth and bring to a boil, reduce heat and cook covered on low for about 30 minutes, stirring occasionally until thickened. Remove from heat.
Toss in parsley, spinach and stir in lemon juice and serve