Shacha (沙茶) is like a cross of XO sauce and bagna cauda, deep flavor and umami rich! It’s a briny medley of dried seafood like salt-cured anchovies and shrimp, cooked down slowly with fried shallot. You can use it as a dipping sauce for hot pot traditionally or use it as a condiment to stir into noodles, fried rice, or sauté with vegetables.
Cover the scallops and shrimp with warm water and soak for 30 minutes. Drain, then tear each scallop into a few pieces. Add the scallops and the shrimp to a food processor fitted with the blade attachment. Pulse about 30 times until shredded and fluffy. To do by hand, shred the scallops with your fingers, and mortar and pestle the shrimp until very finely chopped.
Heat the oil in a medium saucepan or wok over medium heat until shimmering. Add the garlic, ginger, and shallots and fry until starting to brown, about 2 minutes. Stir in the scallops, shrimp, and anchovies, and cook, stirring frequently, until golden brown, about 5 minutes. Remove from the heat and stir in the sesame oil, 10 spice, and cayenne. Once cool, refrigerate up to 6 months. Stir before using.