Trim off the crusts and cut the bread into 1/2-inch (1.3 cm) squares.

Heat the oil in a medium skillet over medium-high heat. When a test piece sizzles, fry as many squares as fit without crowding, working in batches if needed. Lower the heat as needed since bread burns quickly, and stir with a long spoon or spatula. Remove the moment the squares turn a light gold and drain on paper towels or a wire rack. Keep the oil hot enough to brown quickly, but not so hot that it scorches.