Pulse together lemongrass, ginger, scallions, chili, and garlic in a food processor or high powered blender.
Add coconut milk, herbs, lime juice, fish sauce, soy sauce, and sesame oil and blend until smooth, scraping down the sides as needed.
Add fish to an airtight container or ziplock bag and cover with marinade. Turn bag or container a few times to cover fish. Place in fridge and allow to marinate for 15-30 minutes and no more than 1 hour.
Remove fish from marinade and transfer to a baking sheet lined with aluminum foil. Bake for 20-25 or until translucent. Serve over rice and garnish with lime wedges and additional cilantro leaves.