1Place pine nuts on plate; microwave, uncovered, with 650 watts, until lightly toasted, 3 minutes. Set aside to cool.
2Place peppers in dish large enough to hold all three without touching. Cover; microwave with 650 watts, until skins loosen, 15 minutes. Remove and let stand at least 5 minutes. Longer is OK. Peel off skins, then remove stems and seeds.
3Puree peppers with nuts, garlic, cheese, oil and salt in food processor fitted with metal blade. Use right away, refrigerate for up to 5 days, or freeze.
Inspired by a bowl of intensely savory and satisfying French onion soup, these stuffed peppers feature a rich gravy that coats the beef and rice filling, as well as gooey gruyere cheese, and toasty sourdough bread.