For the tempering:
In a large pot, bring the toor dal and 3 cups water to a boil. Reduce the heat to medium-high and simmer until the peas have lost their crunch, but still needing additional cooking, about 20-30 minutes. Then add the onion, tomatoes, serrano peppers, turmeric, salt, and 2 more cups of water. Cook for an additional 20-25 minutes, until the onion is cooked through, and the peas are soft. Add the spinach and heat through over low heat for 5 minutes. While the spinach is cooking, make the tempering.
Heat the grapeseed oil up to almost the smoke point. Add the garlic and spices, making sure they sizzle on contact with the oil. Some will pop. This can take 1-3 minutes depending on your pan and oil used. Don’t burn the garlic, just a golden touch. Add the tempering to the dal. It will make a sound! Stir well, while heating gently for a few minutes. Add the lime juice, taste and adjust. Bon appétit!
You can switch out the spinach for pretty much any other vegetable you want. Vegetables such as chayote, squash, chard, even cucumbers are sublime in here! Just add them earlier, shortly after the onion, tomatoes and peppers. Cook until you like their consistency.