Step 1Broil the peppers 4 inches from the heat, turning to blacken all the sides, about 10 minutes. (You can also roast the peppers on top of a gas flame.) Place the peppers in a paper bag 10 to 15 minutes, then peel off the charred skins. Cut out the membranes and seeds and set the peppers aside.
Step 2Fry the bread in a little olive oil until golden and crisp. When cool, grind the nuts, bread and garlic in a food processor until they are fairly fine.
Step 3Add the ground chile, tomatoes, parsley, salt and pepper to taste, paprika, bell peppers, and Sherry vinegar and process until smooth. With the machine running, gradually pour in the oil. Taste and make sure the sauce has plenty of piquancy and enough salt.