In a large skillet, heat the coconut oil over medium heat. Add the diced onion and sauté for about 5 minutes until softened.
Stir in the minced garlic and grated ginger, cooking for an additional minute until fragrant.
Add the curry powder and ground turmeric, stirring to coat the onions evenly. Cook for another minute.
Pour in the coconut milk and vegetable broth, followed by the fish sauce and brown sugar. Stir well to combine.
Bring the mixture to a gentle simmer, then add the salmon pieces and cherry tomatoes. Cook for about 5-7 minutes, or until the salmon is cooked through and flakes easily with a fork.
Stir in the spinach leaves and cook for an additional 2 minutes until wilted. Season with salt and pepper to taste.
Serve the curry hot, garnished with fresh cilantro and lime wedges on the side.