Preheat the oven to 450F
Line a baking sheet with tin foil and place the red peppers on the sheet
Roast the peppers for 20-25 minutes, turning every 5 minutes til the peppers are soft and black.
Remove the peppers from the oven, wrap in the tin foil and allow to rest for 5 minutes.
Slice the peppers, removing the top, cartilage and seeds. Add the slices to a food processor with the rest of the ingredients except the oil.
Run the food processor and slowly drizzle in the oil, then continue to run the processor for 5 minutes.
When the beef is done, remove it from the slow cooker, pull it apart with forks.
Strain the juices from the slow cooker, discarding the solids
Cut the buns in half, butter and toast. Top each bun with meat and cheese and return to the broiler til the cheese is melted. About 1 minute.
Top sandwiches with chopped gardeniera and aioli.
Cut sandwiches in half and serve with the juice for dipping