In a large mixing bowl, combine the flaked salmon, mashed sweet potato, egg, panko, green onions, garlic, salt, and pepper until the mixture is uniform.
Divide the mixture into 8 equal portions and shape each into a patty approximately 1 inch thick.
In a small bowl, whisk together the mayonnaise, sriracha, dill, and lemon juice until smooth; refrigerate until serving.
Heat the vegetable oil in a large non-stick skillet over medium heat.
Carefully place the patties in the skillet and cook for 3 to 4 minutes per side until a golden-brown crust forms and the interior is heated through.
Remove the cakes from the heat and serve immediately with a dollop of the dill sriracha sauce.