Wash and remove core from peppers; chop coarsely. Peel and chop onions and garlic.

In a skillet, sauté sausages until halfway cooked, then add peppers, onions, garlic. Simmer over low heat until sausages are no longer pink in center (15-20 minutes).

Season to taste with salt, pepper and red pepper flakes. Stir in tomato sauce or puree during last five minutes (may be served with or without sauce).

Fill toasted crusty rolls with mixture and serve.

For make-ahead or to bring on a picnic or for tailgating, split the rolls and butter. Wrap rolls tightly in aluminum foil. Pack sausage filling in a plastic container and keep cold (below 40°F).

When ready to serve, open foil slightly, fill rolls with sausage mixture and rewrap. Heat on BBQ or in 350°F oven for 20-30 minutes (until heated through).