Combine rice, coconut milk, and water in a medium saucepan over medium-high heat. When liquids are bubbling vigorously, reduce heat to low-medium (or move the pan to another burner over low-medium) and cover. Cook, covered, for 15 minutes. Remove from heat and let rest, covered for 10 minutes.
While rice rests, if using bamboo skewers, soak in water for 10 minutes. (This will help prevent burning.)
Finely chop the cilantro, mint, and green onions. Whisk together lime juice, warm water, sugar, and fish sauce until sugar is dissolved. Whisk in herbs. (You can also combine everything in a small food processor and pulse until finely chopped.)
In a large bowl, toss fish in oil until coated. Add turmeric, salt, and black pepper and toss to coat.
Thread mahi mahi onto skewers.
Place skewers on a sheet pan and refrigerate until ready to cook. (If cooking under the broiler you can broil the fish directly on this pan.)
Heat a grill or turn on the oven’s broiler and place a rack about 8 inches beneath the heat source.
Grill skewers or cook them on a sheet pan under the broiler, turning once they are golden brown and cooked on one side, until tender, flaky, and cooked through, 4 to 7 minutes total.
Serve skewers over coconut rice with herb sauce, lime wedges, and chopped peanuts for topping. Enjoy!