Preheat the oven to 400 degrees F and prepare a foil covered baking sheet.
In a small pot, whisk together maple syrup, water, white vinegar, cornstarch, minced garlic, salt, and chili flakes.
Place the pot on the stove over high heat, and bring to a boil. Reduce heat to medium-high, whisk continuously while the liquid simmers, until it reduces and thickens into a syrup, about 3-5 minutes (the syrup should be a little more runny than honey). Remove from heat and reserve to the side.
Rinse salmon fillets under cold water, blot dry with a paper towel, and lay on the prepared baking sheet.
Brush salmon with half of the sauce, and place on the middle rack in the oven to bake for about 18 minutes, until pink and flakes easily with a fork. Glaze salmon mid-way through baking with the other half of the sauce.
Set the stove on high broil, and cook for about 2 minutes longer, until the sauce begins to caramelize.
Garnish with chopped scallions, sesame seeds, and chopped cilantro.