Make a paste: Place ¼ of the salmon in a food processor. Add the dijon mustard, mayonnaise, lemon juice, and paprika. Pulse for a few seconds to form a uniform paste. Set aside.
Add the remaining ¾ of the salmon (cut into chunks) into the food processor and pulse 4 or 5 few times until just combined. There should be very small chunks of salmon in the mixture.
Transfer the salmon mixture into a bowl, and add ½ cup of the panko breadcrumbs, scallions, onions, ¾ teaspoon Kosher salt, and ½ teaspoon ground black pepper. Mix using a rubber spatula. Do not overmix.
Line a baking sheet parchment paper and set aside. Divide the salmon mixture into 4 equal parts, and form 4 patties about ¾ inch thick each. Place patties on the prepared baking sheet and cover with plastic wrap. Refrigerate for at least 30 minutes - this is so they hold their shape.
Meanwhile, make the garlic herb sauce: Mix all the sauce ingredients until smooth. Set aside.
Coat the exterior of the cold patties with the remaining panko breadcrumbs, pressing slightly to adhere on both sides.
Cook the salmon patties: Heat some olive oil on a large non-stick skillet over medium heat. Cook the salmon patties for about 4-5 minutes each side, until golden brown and cooked in the middle.
Assemble: Build the burgers with your favorite toppings and the prepared garlic herb sauce. Serve immediately. Enjoy!