Salmon and Bok Choy Green Coconut Curry

Name: Salmon and Bok Choy Green Coconut Curry
Ingredients: 4 (6–8-oz.) skinless salmon fillets; 2 tsp. kosher salt, divided; 1 (14-oz.) can full-fat coconut milk; 1/4 cup green curry paste; 2 tsp. finely grated peeled ginger (from one 2 piece); 1 garlic clove, finely grated; 1 head of bok choy (about 1 1/2 lb.); 2 Tbsp. fresh lime juice; 4 scallions, thinly sliced; 1/2 cup cilantro leaves with tender stems; 1/4 cup roasted salted cashews; 1 serrano chile, thinly sliced (optional); Steamed rice (for serving; optional)