Preheat the oven to 425°F (220°C). Cut 1½ pounds potatoes into thin discs or half-moons. Cut 2 medium zucchini into thick half-moons, then slice 1 large red onion and 1 large red bell pepper.
Add the vegetables to a large rimmed baking sheet or roasting pan. Add 3 cloves garlic (pressed), 1 can diced tomatoes, 2 tablespoons tomato paste, 4 tablespoons extra virgin olive oil, 1 teaspoon dried oregano, 1 teaspoon salt, black pepper, and half of the parsley. Toss well, then spread everything into an even layer.
Bake at 425°F (220°C) for 50 minutes. The potatoes should be tender and lightly browned, and most of the tomato juices should have reduced into a rich sauce. If the pan still looks very liquid, roast for 5 to 10 minutes longer.
Let the briam cool for 5 to 10 minutes. Top with the remaining parsley and crumbled feta cheese. Serve warm or at room temperature with pita, crusty bread, couscous, or pasta.
