We actually did this with trout and filet mignon one night around the campfire by digging a hole in the ground and then filling it half-way with burning embers, setting both on top, and then covering completely with more burning embers. It took about twenty minutes and was FABULOUS! We called it campside surf and turf.
5 pounds coarse (kosher) salt
4 whole trout, cleaned and gutted
1/4 cup extra-virgin olive oil
Parsley sprigs for garnish (optional)
1. Cover bottom of 15 x 17-inch shallow baking pan with 3 1/2 pounds coarse salt.
2. Wash fish and pat dry with paper towels.
3. Preheat oven to 500 degrees.
4. Place baking pan in oven.
5. Remove pan from oven and arrange fish on hot salt, ensuring that they are not touching. Cover fish completely with remaining salt. Bake 15 minutes.
6. Heat platter under hot running water and dry.
7. Remove fish from oven and crack off top salt. Gently lift fish out with 2 metal spatulas and place on warmed platter. With pastry brush, remove discolored salt from top of fish and from belly cavity.
8. Discard discolored salt in baking pan and transfer remaining salt to another platter. With 2 spatulas, transfer fish onto bed of salt. Drizzle olive oil over fish and garnish with parsley sprigs, if desired.