Gochugaru, a mild, fragrant red-pepper powder, bedazzles this quick salmon dinner. As a key ingredient in Korean home cooking, gochugaru proves that some chiles provide not only heat but fruity sweetness as well. Here, that’s especially true once it’s bloomed in maple syrup, vinegar and butter. If you like shiny things, you may find great pleasure in watching this pan sauce transform into a mirrored, crimson glaze. Try to get long center-cut salmon fillets for uniform thickness and even…