Special equipment: spice grinder or mortar and pestle
Preheat a grill to medium-high.
First grind the garam masala, curry leaves, mustard seeds, and asafoetida in a spice grinder or with a mortar and pestle.
Gently rub each salmon fillet with oil and season with the ground spices and salt. Lightly oil the grill and add the salmon fillets, skin side down. Cook for 5 to 6 minutes and then flip and cook the other side for an additional 5 minutes, until salmon is cooked and flakes with gentle pressure from a fork. Serve the salmon fillets with the Mango Masala.
To make mango masala: Mix the mango, mango juice, cilantro, red onion, lime juice, garam masala, and salt in a bowl and let sit for 5 minutes.
*Can be found at specialty Asian and Indian markets.