Over a small bowl, used a sharp paring knife to cut rind from the oranges and lemons, down to the flesh. With each segment, slice the fruit between the two membranes so you just get the flesh. Let the citrus juice drip into the bowl as you cut.
Slice jalapeño crosswise into very thin slices (1/16 inch). Blend all ingredients together and set aside while you make the fish.
Note: Have ingredients for the sautéed vegetables pre-cut before you start the fish.
Cut opah into 6-ounce portions. Season with salt and pepper. Heat sauté pan on high, bringing oil to smoking point.
Gently place opah filets in sauté pan. Cook on high for 3 to 4 minutes, until a nice brown crust develops. Gently and carefully flip opah over.
Reduce heat to medium and cook for another 5 minutes or until fish is cooked to desired doneness. Let the fish rest while you sauté the vegetables.
Trim bottom off bok choy, rinse with water and slice into 1-inch chunks. Heat a sauté pan and add oil. Add shallot and bell pepper and cook for 1 minute. Add bok choy and lightly toss. Add sauce, toss and continue cooking over moderately high heat 2–3 minutes.
Whisk all ingredients together in a small bowl and set aside.
To serve, place sautéed vegetables on a plate. Top with opah, then 2 tablespoons citrus salsa.