How to Make It
In a large glass or ceramic baking dish, combine 1/2 cup of the oil with 3 tablespoons of the chili sauce, the cilantro, 1 tablespoon of the pickled ginger and the minced garlic. Add the shrimp and toss well. Cover tightly and refrigerate overnight, stirring once or twice.
In a mini processor, combine the vinegar with the remaining 2 tablespoons of chili sauce, the remaining 1 teaspoon of pickled ginger, the mustard and smashed garlic clove and puree until smooth. With the machine on, add the remaining 1/4 cup of oil in a thin stream and process until emulsified. Transfer to a bowl and add the avocado, tomato and scallions. Season with salt.
Light a grill. Scrape some of the marinade from the shrimp and grill them over high heat until opaque throughout, 3 to 4 minutes. Transfer the shrimp to a platter and season with cracked pepper. Serve with the salsa and lime wedges.