Warm the olive oil and saute the garlic and onion in a soup pot for a few minutes. Add the vegetable broth and lentils. Bring to a boil then simmer covered about 10 minutes. Add the potatoes and carrots. Simmer another fiftenn minutes. Add the spinach, cumin, coriander, cayenne, lemon zest, and lemon juice. Simmer until the spinach is wilted and the lentils are tender. Season to taste with salt and pepper. Stir in fresh mint and parsley and serve.