Pier 23 Dungeness Crab Cake

Name: Pier 23 Dungeness Crab Cake
Ingredients: 1 cup hot vinegar; 1 tablespoon sugar; 1 tablespoon salt; Celery sticks, for pickling; 1 tablespoon hot sauce; 1 tablespoon mayonnaise; 1 tablespoon whole-grain mustard; 1 lemon, zested and juiced, plus lemon wedges, for serving; 1/2 bunch scallions, sliced thin; 2 tablespoons finely chopped fresh parsley; 2 cups panko breadcrumbs; 1 1/2 pounds Dungeness crab meat; 1 egg white; 1/4 cup canola oil; 1 cup mixed red and green butter lettuces; Pepitas, recipe follows; 2 tablespoons champagne vinaigrette; Mustard Crema, recipe follows; 1 cup pumpkin seeds; 1/2 cup canola oil; Pinch salt; 1 cup mascarpone; 1/4 cup whole-grain mustard; Zest and juice of 1 lemon; 2 tablespoons heavy cream; Salt