Cut the end off the fennel bulb and cut in half. Slice as thinly as you can by hand or on a mandoline. Also set aside the fennel fronds to garnish the finished salad.
Next supreme the orange. Cut a tiny bit off the base, then stand it up and slice the peel off in sections so the flesh is exposed. Carefully take your knife and slice in between each membrane down to the center to get perfect slice with no skin.
Once you have all your orange slices, juice the rest of the orange into a bowl or blender. Add your olive oil and salt and pepper and whisk or process to make a vinaigrette.
Add fennel and orange to a medium bowl.
Flake the trout into small pieces. Add to the fennel and orange, then add the vinaigrette. Finally, add the fennel fronds. Stir together and serve. Enjoy!