Heat the oven to 425°F. Toss zucchini and bell pepper with roasting oil and vegetable salt and roast on a wide rimmed pan for 20 to 25 minutes, stirring once, until tender with browned edges. Cool for 10 minutes.
Meanwhile, boil orzo in water with the tablespoon salt until fully tender. Drain thoroughly and spread in a shallow dish for 10 minutes.
Whisk dressing oil, lemon juice, zest, oregano, dressing salt and pepper. Toss half through the warm orzo.
Fold cooled roasted vegetables, beans, parsley and feta into the pasta with remaining dressing. Serve cool or refrigerate promptly in a covered container.
Stir before serving and refrigerate leftovers within 2 hours.