Greek-Style Stuffed Peppers

lean ground beef

frozen chopped spinach, thawed and squeezed dry

medium zucchini, coarsely grated (about 2 cups)

small onion, minced (about 1 cup)

bulghur

egg, lightly beaten

dried oregano

salt

Freshly ground black pepper

red bell peppers, halved lengthwise, cores and ribs removed

low-sodium stewed tomatoes, finely chopped

crumbled feta cheese