Preheat the oven to 350 degrees F
Place the salmon on a sheet pan, skin side down
Brush with olive oil and sprinkle with salt and pepper
Roast for 15 to 20 minutes, until just cooked
Remove from the oven and cover tightly with aluminum foil
Allow to rest for 10 minutes and refrigerate until cold
Meanwhile, place 2 tablespoons of the butter, 2 tablespoons olive oil, the onion, celery, red and yellow bell peppers, parsley, capers, hot sauce, Worcestershire sauce, crab boil seasoning, 1/2 teaspoon salt, and 1/2 teaspoon pepper in a large saute pan over medium-low heat
Cook until the vegetables are soft, approximately 15 to 20 minutes
Cool to room temperature
Break the bread slices into pieces and process the bread in a food processor fitted with a steel blade
You should have about 1 cup of bread crumbs
Place the bread crumbs on a sheet pan and toast in the oven for 5 minutes until lightly browned, tossing occasionally
Flake the chilled salmon into a large bowl
Add the bread crumbs, mayonnaise, mustard, and eggs
Add the vegetable mixture and mix well
Cover and chill in the refrigerator for 30 minutes
Shape into 10 (2 1/2 to 3-ounce) cakes
Heat the remaining 2 tablespoons butter and 2 tablespoons olive oil in a large saute pan over medium heat
In batches, add the salmon cakes and fry for 3 to 4 minutes on each side, until browned
Drain on paper towels; keep them warm in a preheated 250 degree F oven
Serve hot and fresh!
