A small handful of whole parsley leaves, for garnish
Instructions
Poach the leeks: Keeping a small amount of the root end attached, trim off any excess bits of root and dirt from the leeks. Cut off the tough, dark green ends and discard them (or save them to use in a stock). If you have particularly large, thick leeks, take off the two outermost layers and discard them. For medium leeks, just take off one layer. Rinse off any dirt. If you still see dirt poking up through the inner layers, you can take off another layer until they seem clean.
Cut the leeks crosswise into roughly 6-inch (15 cm) pieces and place them in a 5- to 6-quart (4.7 to 5.7 L) Dutch oven or wide and deep pot. The leeks should fit comfortably across the width of the pot.
Add 2 quarts (1.9 L) water, the wine, kosher salt, and garlic cloves to the pot with the leeks. Place the pot over high heat and once it comes to a simmer, reduce the heat to maintain a gentle simmer for poaching. Lay a sheet of parchment paper over the leeks and then place a salad plate on top to weight it down (this is to help keep the leeks submerged).
Poach the leeks until they are quite tender but not overly soft, 25 to 30 minutes, depending on the size of the leeks. The point of a sharp knife should be able to slide into the thickest part of the leek with minimal resistance, but the leeks should not be so soft that their inner layers are starting to slide out. While they are cooking, if there are any bits of leek bobbing above the surface, just give them a little spin from time to time to help them cook evenly.
Gently lift the poached leeks out of the poaching liquid and place them on a plate to cool to room temperature. Discard the garlic and poaching liquid.
Meanwhile, make the gribiche: Set up a small bowl of ice and water. Bring a small pot of water to a boil. Plunge the cold eggs straight from the fridge into the boiling water and boil gently for 12 minutes. Remove the eggs and immediately shock them in the ice bath until chilled through, about 15 minutes.
Peel the eggs and separate the whites from the yolks. Roughly chop the whites so that they have some variety of size but no pieces larger than a chickpea and set aside.
Place the yolks in a medium bowl and mash them with a fork until they have a crumbly texture with no big lumps, marbles, or pebbles. Add the mustard and lemon juice and whisk until well combined. Pour in the olive oil and whisk to combine (don’t worry, this is a broken sauce, not an emulsified one, so you add all the olive oil at once).
Add the chopped egg whites, capers, dill, parsley, tarragon, kosher salt, and cayenne and stir with a spoon to combine.
To assemble: Halve the leeks lengthwise, then remove the outer layer and discard it. If you see dirt, you can keep removing layers of leek until they look clean. Then cut them in half again, crosswise, leaving you with pieces 2 to 3 inches (5 to 7.5 cm) long.
Arrange the leeks on a platter, cut side up. Cover them with large, artful splashes of gribiche, then dollop them with the smoked trout roe. Garnish the dish with whole parsley leaves and serve immediately.