How to Make Tuna en Papillote

Julienne carrots, leeks, and celeriac and cook in butter. Season the tuna on both sides with salt and pepper and brown in oil over high heat. Place in the center of a rectangle of parchment, put the julienne on top, add a slice of herb butter, and drizzle with white wine.

Brush the edges of the parchment with lightly beaten egg white.

Fold over the edges to seal.

Bake until the bags puff, then open at the table.