Clearly this recipe can be done with salmon, kokanee, char or really any fish you want. I just like it with trout. The herbs are also open to improvisation; the combination I use is what I like. Serve these with a green salad or as the filling in a sandwich.
Cook the minced onion with the butter in a small pan over medium heat until translucent, but not browned. Remove from the pan and let cool.
Chop the trout meat with a knife into bits. You can chop very roughly and then pulse a couple times in a food processor, but you want the trout in little pieces, not as a paste.
Mix all the remaining ingredients (except the frying oil) together in a large bowl. Form cakes with your hands. I like them about the width of my palm. You will need to wash your hands a couple times to remove debris; this helps you make cleaner, nicer cakes.
Let the cakes sit in the fridge for 20 minutes or so -- this lets the breadcrumbs absorb moisture, which helps your cakes hold together.
Heat the frying oil in a large, wide pan over medium-high heat. Fry as many cakes as will fit in one layer without touching. Cook them until each side is golden brown, about 4 to 6 minutes per side. Serve hot.