1. Prep the shrimp:
Pat the shrimp dry and season lightly with salt and pepper. Set aside.
2. Sauté the aromatics:
In a large skillet or saucepan over medium heat, warm the oil. Add the onion and cook until translucent, about 4 minutes. Stir in the garlic and ginger; cook another 30 seconds until fragrant.
3. Toast the spices:
Sprinkle in the curry powder, turmeric, cumin, and red pepper flakes (if using). Stir constantly for about 1 minute to bloom the spices without burning.
4. Build the sauce:
Pour in the coconut milk and stir to combine, scraping up any browned bits. Add the diced tomatoes, fish sauce, and sugar. Bring to a gentle simmer.
5. Cook the shrimp:
Slide the seasoned shrimp into the simmering sauce in a single layer. Cook uncovered for 3–4 minutes, until the shrimp turn pink and opaque.
6. Finish & season:
Stir in the lime juice. Taste and adjust seasoning with salt, pepper, or a splash more fish/soy sauce as needed.
7. Garnish & serve:
Remove from heat. Sprinkle with chopped cilantro or basil. Serve hot over jasmine rice or with warm naan to soak up the creamy curry.