Cook rice according to package directions.
Melt butter in a large ovenproof nonstick skillet over medium-high heat. Add leek and mushrooms; cook 5 minutes or until tender. Remove from heat. Stir in 1/2 teaspoon sea salt, 1/4 teaspoon pepper, and next 3 ingredients.
Combine rice and mushroom mixture in a large bowl.
To assemble 2 fish bundles, place 1 sheet wax paper on a work surface. Arrange 3 bacon slices, 1 inch apart, on paper. Place 1 fillet, skin side down, across bacon. Spoon half of stuffing mixture evenly over fillet. Top with 1 fillet, skin side up. Wrap bacon around stack; tie bundle with string. Repeat with remaining bacon, fish, and stuffing mixture. Sprinkle each fish bundle with remaining 1/4 teaspoon each of sea salt and pepper.
Wipe skillet clean. Heat 1 tablespoon oil in pan over medium-high heat. Add fish bundles; cook 2 minutes on each side or until bacon is crisp.
Place skillet in oven, and bake at 425° for 8 minutes or until fish is opaque, turning once. Cut bundles in half, and serve over tomato slices. Drizzle with remaining 1 tablespoon oil. Garnish, if desired.