Salmon with Scotch Bonnet-Herb Sauce and Onion Toasts

In a large glass baking dish, blend 2 tablespoons of the olive oil with the mustard. Add the salmon fillets, turn to coat and refrigerate. Preheat the oven to 500 °F. In a small saucepan, boil the Riesling over moderately high heat until reduced to 1/4 cup, about 7 minutes. Remove from the heat and let cool. In a medium bowl, whisk the mayonnaise with 6 tablespoons of the olive oil. Whisk in the wine reduction, chives, basil, cilantro and Scotch bonnet. Season with salt and pepper. Melt the butter in a medium skillet. Add the onion and cook over moderate heat until softened and starting to brown, about 8 minutes. Place the baguette toasts on a baking sheet and top with the onion. Bake in the upper third of the oven for 1 minute. Meanwhile, in each of two medium skillets, heat 1 tablespoon of olive oil until shimmering. Season the salmon with salt and pepper and add 3 fillets to each skillet, skin side down. Cook over high heat until the skin is browned and crisp, about 4 minutes. Turn the fillets and cook over moderately high heat until an even pink throughout, about 5 minutes. Spoon the chile-herb sauce onto plates. Top with the salmon fillets and serve with the onion toasts. Make Ahead: The salmon can marinate in the refrigerator overnight. Wine Recommendation: The elegant fruit in a Riesling can highlight the equally refined hint of fruit in the Scotch bonnet sauce here. But the sauce isn't just fruity, it's spicy. A bottling from the Rheingau area of Germany, like the 2003 Schloss Vollrads Kabinett, offers a bit of sweetness to cool the heat.