Prepare the Brine: Dissolve sea salt and sugar in warm water. Submerge the fish fillets in the brine and let them sit for 15 minutes.
Heat the Olive Oil: In a deep skillet, heat the olive oil to 180°F (82°C). Add minced garlic and a mix of chopped herbs.
Poach the Fish: Remove fish from the brine, pat dry, and gently place them into the warm olive oil. Poach at a gentle simmer for about 5 minutes per inch of thickness.
Monitor the Temperature: Keep the oil temperature steady. Use a thermometer to ensure it does not exceed 180°F.
Finish and Serve: Once the fish is opaque and flakes easily, remove from the oil. Drain on paper towels, season with black pepper, and serve with lemon slices.