Rinse lentils and place in a saucepan with enough water to cover. Bring to a boil. Reduce heat to low, cover pot, and simmer over low heat for 20 minutes. Drain.
In a bowl, stir together tomato puree and yogurt. Season with garam masala, turmeric, cumin, and chile powder. Stir until creamy.
Heat oil in a skillet over medium heat. Stir in onion, garlic, and ginger; cook until onion begins to brown. Stir in spinach; cook until dark green and wilted. Gradually stir in yogurt mixture. Then mix in tomatoes and coriander.
Stir lentils and mixed beans into mixture until well combined. Heat through, about 5 minutes.