In a food processor, pulse the bread for 40-60 seconds until the bread resembles coarse crumbs. Pour the crumbs in a large bowl. Add the salmon chunks to the food processor and pulse until the salmon is ground and sticks together (about 30-60 seconds). Add the salmon to the large bowl.To the salmon and breadcrumbs add the remaining ingredients: lemon juice, red onion, mayonnaise, mustard, fresh herbs, salt and pepper. Stir the ingredients together.Form the ingredients into hamburger patties.In a large skillet (I use a large cast iron skillet), over medium-high heat, melt 1 tablespoon of butter or olive oil. Once the pan is hot, add the salmon burgers and cook for 5 minutes on each side, until lightly brown.Serve warm with lemon wedges (optional).