Lemony Red Lentil and Onion Soup

Measure the lentils, vegetable broth, turmeric and some salt into a medium saucepan. Add a couple teaspoons of olive oil if desired.Bring to a boil, then reduce the heat to a simmer and cook until the lentils are tender and beginning to fall apart, between 20 and 30 minutes.Carefully puree with a hand blender. Hold on very low heat until the onions are finished.While the lentils are cooking, caramelize the onions in a large skillet with a little olive oil. Start over medium high heat, then reduce to low when the onions start to take on some color. Add in the cumin and grainy mustard, then stir every once in a while. Cook until the onions are very soft and a lovely color.Stir the onions into the lentils and squeeze the lemons until you have the level of flavor you desire, add more liquid and adjust the seasoning as needed.To serve, warm the rice (I used the microwave) and wilt the spinach (I used the same skillet I cooked the onions in). Ladle the soup into a large bowl and add a serving of spinach and rice. Garnish with lemon slices or Greek yogurt, as desired.