Green Goddess Salmon Burgers

For the salmon patties:

• 1 pound Salmon fillet (450g)
• ¾ cup panko breadcrumbs
• 1 egg
• 2 tablespoons olive oil (plus 2 tablespoons for pan-frying the patties)
• 1 teaspoon Dijon mustard
• 1 teaspoon tarragon (minced)
• 1/2 teaspoon salt
• 1/8 teaspoon black pepper
• 1 teaspoon paprika
• 1 pinch cayenne pepper
• 1/4 teaspoon garlic powder
• 1/4 teaspoon onion powder

For the green goddess dressing:

• 1/2 cup mayonnaise
• 1/2 cup Greek yogurt
• 2 tablespoons tarragon (chopped)
• 1 tablespoon Dill (chopped)
• 1/4 cup scallions (chopped)
• 3 tablespoons chives (chopped)
• 2 tablespoons parsley (chopped)
• 3 tablespoons basil (chopped)
• 2 anchovy fillets
• 1 tablespoon lemon juice
• 1/4 teaspoon salt
• 1/8 teaspoon black pepper

To assemble the burgers:

• 3 Brioche burger buns (cut in half, toasted and buttered)
• 1/2 small red onion (thinly sliced)
• 1 avocado (sliced)
• 3 cups arugula