Cook the sushi rice according to package directions, then transfer to a large bowl while still hot. In a small bowl, whisk together the rice vinegar, sugar, and salt until the sugar dissolves completely. Pour this mixture over the hot rice and gently fold it in with a wooden spoon or rice paddle using a cutting motion rather than stirring, which prevents the rice from becoming mushy. Let the rice cool to room temperature while you prepare the other components.
While the rice cools, toast the sesame seeds in a dry skillet over medium heat for 2-3 minutes, stirring frequently until fragrant and lightly golden. Transfer to a small bowl. Thinly slice the spring onions on a bias, cut the salmon fillets into 1-inch cubes, and slice the avocado. I like to prep the avocado last so it doesn't oxidize and brown before serving.
In a small bowl, whisk together the maple syrup, sesame oil, tamari, garlic powder, mirin, and ground ginger until fully combined. Pour this marinade into a medium skillet over medium-high heat and bring to a simmer. Let it cook for 2-3 minutes, stirring occasionally, until it thickens slightly and becomes glossy—this concentrates the flavors and creates the perfect coating for the salmon.
Add the salmon cubes and sliced spring onions to the thickened teriyaki glaze in the skillet. Cook over high heat for 2-3 minutes, gently tossing occasionally, until the salmon is just cooked through but still tender in the center. The exterior should be nicely glazed and caramelized. I prefer to slightly undercook the salmon rather than overcook it—it continues cooking slightly from residual heat and stays more moist.
Fold the toasted sesame seeds from Step 2 into the cooled sushi rice, reserving a small amount for garnish if desired. Divide the seasoned rice between serving bowls as the base. Arrange the edamame, avocado slices, and the glazed salmon with spring onions on top of the rice, creating an organized, appealing presentation.