Start by chopping the onion finely and mincing the garlic and ginger. Cut the salmon into equal portions if needed, ensuring even cooking. Keep all spices measured and ready for quick use during cooking.
Heat oil in a pan over medium heat and add the chopped onions. Cook until they turn soft and slightly golden, then stir in garlic and ginger. Let them cook for a minute until fragrant and aromatic.
Sprinkle in turmeric, cumin, coriander, and chili powder. Stir well to coat the onion mixture with spices evenly. Cooking the spices briefly helps release their essential flavors.
Add tomato paste and mix thoroughly to combine with the spices. Pour in the coconut milk and stir until the mixture becomes smooth and creamy. Let it simmer gently to allow the flavors to blend.
Place the salmon fillets into the curry sauce carefully. Let them cook for about 6–8 minutes, turning once if needed. The salmon should be tender and cooked through but not overdone.
Squeeze fresh lime juice into the curry for a bright, tangy flavor. Taste and adjust salt if needed. Garnish with fresh cilantro before serving.