Fill a medium pot with enough oil to reach a depth of 1 1/2 inches and heat until it registers 375 degrees on a deep-fry thermometer. In a medium skillet, heat the olive oil over medium-high heat. Add the bread, almonds and garlic and cook, stirring, until the nuts are golden, 3 to 4 minutes. Transfer to a food processor. Using the same skillet, add the vinegar and bring to a boil. Remove from the heat, stir in the pimientos and 1/3 cup water and season with salt and pepper. Add to the almond mixture in the food processor and puree, scraping down the sides as needed, for 1 minute. Transfer to a serving bowl and cover with plastic wrap.
In a large bowl, season the flour with 1 teaspoon salt and 1/4 teaspoon pepper. Coat each oyster with the flour, shaking off any excess. Working in small batches, fry the oysters until browned, 2 to 3 minutes, allowing the oil to return to 375 degrees between batches. Using a slotted spoon, transfer to paper towels to drain. Serve with the dipping sauce.