SERVES 8 – 14

For a smooth and successful mayonnaise—one that doesn't separate—be sure that all the ingredients are at room temperature before you start whisking.

FOR THE MAYONNAISE:
2 egg yolks, at room temperature
1 tsp. dijon mustard
Salt and freshly ground black pepper
1⁄2 cup sunflower oil
1⁄2 cup olive oil

FOR THE SALMON:
1 whole cleaned salmon (about 8–9 lbs.)
Salt and freshly ground black pepper
5 large sprigs flat-leaf parsley
2 dried bay leaves, lightly crushed
1 lemon, cut into thick slices
1⁄2 small yellow onion, thickly sliced
1 cup white wine

1. For the mayonnaise: Combine yolks, mustard, and salt and pepper to taste in a medium bowl and whisk to combine. (A mortar and pestle may also be used.) Slowly drizzle in oils while whisking constantly, to ensure smoothness. (You may add up to 5 tsp. water to thin the mayonnaise, if necessary.) Adjust the seasonings. Transfer mayonnaise to a small serving bowl and refrigerate until ready to use.

2. For the salmon: Season salmon inside and out with salt and pepper to taste. Arrange salmon on the rack of a large fish poacher. Lower rack into poacher and layer top of salmon with parsley, bay leaves, lemon slices, and onions. Pour wine and 10–12 cups water around the sides of the salmon—not directly onto the fish. (The liquid should come halfway up the sides of the salmon.) Arrange poacher over 2 burners, cover, and bring to a simmer over medium heat. Reduce heat to medium-low and simmer, covered, until salmon is just cooked through, about 30 minutes. Remove poacher from heat, lift rack out of liquid, and carefully set rack over the poacher at a slant to let drain and cool slightly. Transfer salmon to a large platter and serve at room temperature with chilled mayonnaise on the side.