Melt coconut oil in a large soup pot over medium heat, then sauté shallot until softened for 3-4 minutes. Add garlic and ginger, sautéing for 1-2 minutes until fragrant, then add red curry paste and sauté for 1 more minute.

Slowly pour in chicken broth, scraping the bottom of the pot, then add coconut milk, Tamari, fish sauce, coconut sugar, dried basil, salt, and pepper to taste. Bring the soup to a bubble on high heat, then reduce to medium-low and simmer for 10 minutes, stirring occasionally.

Increase heat to high to bring the soup to a rolling boil, then add shrimp, mushrooms, and spinach. Simmer for 4-5 minutes until the shrimp are fully cooked through, then squeeze in the juice of half a lime and stir. Serve immediately with cooked rice, lime wedges, and chopped fresh cilantro.