Whisk eggs until light and frothy.
Add mayo, mustard, lemon juice, cayenne, onions, salt, and pepper. Stir to combine.
Fold in panko until batter thickens.
Break crab meat apart gently and fold into batter.
Cover and refrigerate for 1 to 2 hours.
Form chilled mixture into golf ball-sized rounds. Do not compress tightly.
Heat oil in a deep pan over medium-high heat.
Fry in batches until deep golden brown on all sides, about 3 to 4 minutes.
Drain on a rack or paper towels and serve with rémoulade.