Heat oven to 375°F. Heat oil in medium skillet over medium-high heat. Add onions; cook until soft and translucent, about 10 minutes. Add pimientos and garlic, cook until fragrant, about 1 minute. Stir in bonito, tomato sauce and olives. Using spoon, break up bonito into small pieces. Cook mixture until tomato sauce begins to boil, about 5 minutes more. Stir in parsley; season with adobo; set aside to cool.
Place pastry round on greased foil-lined baking sheet; spoon 1/4 cup bonito mixture in middle of dough round. Using pastry brush, paint beaten egg around edges of dough; place additional dough round on top. Using your fingers, gently press edges of dough together to seal. Repeat with remaining filling to form 6 mini empanadas. Brush beaten eggs over tops. Transfer baking sheet to oven. Cook until dough puffs, turns light golden brown and is cooked through, about 20 minutes. Serve warm.
After gently pressing the edges together, transfer the raw empanadas to the refrigerator to rest for 10 minutes. This dries the egg wash and fuses the dough together. You’ll be left with perfect empanadas – pastry that reveals its buttery flakes and a moist filling that stays put.