In a medium bowl, mix together the flour, sugar, and salt.

In a separate bowl, whisk the softened butter until it is completely smooth and mayonnaise-like in texture.

Using a stiff spatula or spoon, beat the egg whites into the dry ingredients until completely incorporated and smooth.

Whisk in the softened butter by thirds, scraping the sides of the bowl as necessary and whisking until the batter is creamy and without any lumps.

Transfer the batter to a smaller container.

Preheat the oven to 400°F.

Make a 4-inch circular stencil. Place a Silpat on the counter.

Place the stencil in one corner of the sheet and spread the batter over the stencil.

Sprinkle each cornet with a pinch of black sesame seeds.

Bake for about 4 to 6 minutes, or until the batter is set.

Open the oven door and place the baking sheet on the door.

Flip a cornet over on the sheet pan, sesame seed side down, and place a cornet mold at the bottom of the round.

Fold the bottom of the cornet up and around the mold and carefully roll upward.

Return the rolled cornets to the oven and bake for an additional 3 to 4 minutes.

Remove the cornets from the oven and allow to cool slightly.

Gently remove the cornets from the molds and cool on paper towels.

For the Salmon Tartare: Finely mince the salmon fillet and place it in a small bowl.

Stir in the remaining ingredients and taste for seasoning.

Cover the bowl and refrigerate the tartare for at least 30 minutes.

For the Sweet Red Onion Crème Fraîche: Rinse the red onions under cold water and dry them.

Whisk the crème fraîche until it holds soft peaks.

Fold in the chopped onions and season to taste.

Fill the top ½ inch of each cornet with onion cream, leaving the bottom empty.

Spoon about 1 ½ teaspoons of the tartare over the onion cream and garnish with a chive tip.