Position rack 4-6 inches from the heating element and preheat the broiler.
Season salmon all over with salt and pepper. In a small bowl stir together the Thai sweet chili sauce, sambal oelek, and mustard.
Pour the mixture into a large cast-iron skillet. Set skillet over medium-high heat until the mixture boils.
Lay the salmon skin side up, in the sauce. Cook the salmon until it turns pale pink about 2 minutes, then move the skillet to the oven and broil
until the skin gets crispy about 3-4 minutes.
Remove the salmon from the oven and place on a serving platter pour the sauce from the skillet over the salmon.
Add ¼ cup of water to the skillet and cook over high heat, stirring and scraping until the sauce thickens. Pour the sauce from the skillet onto the salmon. Note***( I skipped this step and just spooned the sauce from the skillet but it's in Chrissy's recipe so it's optional) Serve immediately.