Get ready. Bring a medium pot of water to a boil over high heat. Line a sheet tray with paper towels.

Poach the shrimp. Once boiling, season the water generously with salt and turn the heat to medium. Add the shrimp and simmer until they turn opaque, about 2 minutes. Use a slotted spoon to transfer them to the prepared sheet tray and spread in one layer so they get nice and dry.

Make the dressing. Add the garlic and egg yolk to a small mixing bowl. Whisk to combine. As you whisk, very slowly incorporate the olive oil. Start with one drop at a time and whisk to incorporate, then another drop, then a drizzle. Add in small drizzles until you’ve emulsified all of the oil, adding a pinch of salt halfway through (about ¼ teaspoon). The sauce should be thick and pale yellow.

Season the dressing. Zest in one lemon, then slice it in half, squeeze in half the juice, and whisk to combine. Taste and add more lemon juice and/or salt if you’d like. Mix in the capers, Dijon mustard, paprika, and Worcestershire sauce (if using).

Mix the salad. Pat the shrimp dry with paper towels one more time and transfer to a large mixing bowl. Add the celery and green onions and toss to combine. Mix in the dressing to taste (I use all of it).

Chill. Put in your fridge for 20 minutes or so to chill, or up to overnight.

Finish. Slice an avocado in half, remove the pit, then cut the flesh into large cubes, about the same size as the cooked shrimp. Very gently fold the avocado into the shrimp salad.

Serve. Line a serving platter with the romaine lettuce and squeeze on half of a lemon. Top with the shrimp salad and finish with freshly grated black pepper and more parsley. Slice any remaining lemon into wedges and place along the platter for everyone to help themselves.