In a skillet with high sides, whisk together coconut milk, water and curry paste. Bring to a boil, reduce to a simmer, and add red lentils. Let simmer for 22 to 25 minutes, just until the red lentils are tender but still hold their shape.
Remove pot from heat and stir in spinach until wilted. Serve curry over cooked grain, with a dollop of yogurt, if desired.
Notes
Tips & Tricks: I'll often keep a jar of store-bought curry paste for this dish. You can find these curries in most grocery stores.