a bunch of fresh basil leaves (Thai or sweet basil)
Chop the celery sticks horizontally into moon-shaped pieces. Slice the red bell peppers into pieces approximately the same size. Rinse and dry the basil, then stack the leaves on top of each other. Roll the basil leaves lengthwise into a tight cigar, then slice into the cigar thinly to create long, thin strips. Set the basil, peppers and celery aside.
Heat the oil in a nonstick frying pan or skillet over medium-high heat.
Season the fish filets with salt and pepper. Add them to the skillet, skin side down, being careful to leave plenty of space around each fish filet (save some to the side and pan-fry them in batches if you don't have space in your skillet for all of them). As you add each filet, press down firmly on the filet with a spatula to make sure you brown the skin. Keep cooking the fish skin side down for about 3-4 minutes, until the sides of the fish start to turn opaque.
Carefully flip the fish over and cook for another 1-2 minutes until the fish flakes easily with a fork and is completely opaque. Transfer the fish to a serving plate and continue pan-frying the fish until all of the filets are cooked.
Add the garlic to the skillet and stir-fry for about a minute. Add in the oyster sauce, soy sauces, sugar, fish sauce and stock. Add the bell peppers and celery and stir fry for another minute, then stir in the basil leaves and pour the entire sauce over the fish. Serve with steamed white rice.
Recipe by Grits and Chopsticks at https://www.gritsandchopsticks.com/the-gravy-train/2018/07/thai-fish-with-basil-sauce.html