In a large soup pot, over medium heat, melt the oil.
Add shallot or onion; saute until softened; 3 – 4 minutes.
Add garlic and ginger; sauté until extremely fragrant; 1 – 2 minutes.
Add red curry paste; be careful, as it may spit a bit; sauté for 1 more minute.
Slowly pour in chicken broth while scraping up any bits from the bottom of the pot; add coconut milk, soy sauce, fish sauce, coconut sugar, dried basil and salt and pepper, to taste.
Turn heat up to high and bring the soup to a bubble; turn heat down to medium-low and simmer for 10 minutes; stirring occasionally.
Turn heat back up to high and bring soup to a rolling boil; add shrimp, mushrooms and spinach.
Turn heat to medium low and simmer until shrimp are fully cooked through; 4 – 5 minutes; then squeeze in the juice of 1/2 lime; stir.
Serve soup with cooked rice, lime wedges and chopped fresh cilantro.