Add coconut oil to a large skillet or wok over medium-high heat. Add shallots, garlic, ginger, and jalapeño, and sauté until soft and fragrant, around 5 minutes.
Add sweet potatoes, and stir them until coated with oil. Add the curry paste, and stir until all ingredients are combined.
Add coconut milk and vegetable broth, and bring mixture to a simmer over medium-high heat. Once simmering, turn the heat down to medium-low, and cook until the sweet potatoes are fork tender, around 30 minutes.
Once the sweet potatoes are done, the curry sauce should be slightly reduced. Add the spinach, and cook for 5 more minutes, until the spinach has wilted somewhat.
Add the crushed peanuts, cilantro, and fish sauce. Stir until well incorporated, then serve with rice or a side of your choosing.