Swedish Shrimp Toast (Räkmacka)

Bring a medium pot of water to a rapid boil over high heat, then remove it from the heat and let it stop boiling. Add the thawed shrimp, cover with a lid, and poach the shrimp until they’re pink and opaque, 4 to 5 minutes. Meanwhile, fill a medium bowl with cold water and ice. Drain the shrimp and transfer them to the ice bath, then let them sit until fully cooled. Drain and pat them dry, then remove the tails and cut them into ½-inch pieces. (Devaining optional.)

Meanwhile, to a tall cylindrical container, add the egg, Dijon, and lemon juice. Gently pour in the oil. Using an immersion blender, place it so it's touching the bottom of the container, then slowly blend, keeping it in place. Once the ingredients at the bottom are emulsified and you can see it starting to thicken, slowly and gently move the blender up while pulsing to slowly incorporate more of the oil. Continue this until all the oil has been incorporated and the mayo is thick. If it’s not as thick as you’d like, continue adding oil little by little and blending it in slowly until it reaches the desired consistency. Season with salt and pepper, then fold in the chopped herbs.

Spread a generous amount of the herb mayo onto the toast, then add a few lettuce leaves, followed by a generous amount of shrimp. Garnish with a quartered egg, more dill, chives, and a lemon slice.