Rinse lentils and soak for 20-30 minutes. Strain the water from the lentils.

In a large sauce pan, add 3 cups water, salt, soaked lentils, turmeric, and Madras curry powder.  Bring to a boil, then reduce the heat to low-medium.  Cook for 20-30 minutes, add more water (about ½ cup), if it is too thick.  Cook until lentils are very soft and well cooked, mash them, and set aside.  

In a small sauce pan, add oil.  When the oil is hot, add mustard seeds, cumin seeds, and dry red chili broken in half.  When the mustard seeds start popping then add chopped onions, garlic, and curry leaves.  Cook until onions are light brown.

Add chopped tomatoes, place the lid on the pot, and cook for 5 minutes or until soft.  Add chopped spinach and keep stirring for about 5 minutes with the lid off.  Do not overcook the spinach.  

Add the cooked red lentil mixture and cook for 2 minutes.

Add chopped cilantro, salt to taste, and simmer for another 2 minutes.

Remove from stove and add fresh-squeezed lime juice.  Eat with rice or flatbread.