Fill a pot halfway with water and add a teaspoon of salt. Bring the pot to a boil and add the orzo pasta. Cook, stirring occasionally for 9-10 minutes for al dente, or according to package directions. Rinse with cold water to stop the cooking and drain. Set aside.
Heat the grill to high heat, about 450 degrees. Place the red pepper directly on the grates.
Slice the zucchini into rounds, crosswise about 1/2-3/4" thick. Chunk the red onion into 1" pieces.
f grilling, skewer the zucchini slices (skewer on the thin side, so that more of the flesh can get the char of the grill). Separate the layers of onion and loosely skewer. Brush 2 tablespoons olive oil over the onion and zucchini and sprinkle with salt and pepper.
In a large bowl, combine, orzo, red pepper, zucchini, onion, olives, tomatoes, green onions, parsley and feta cheese. Toss to combine.
In a small bowl combine the lemon zest, juice, olive oil, dijon, garlic, oregano, kosher salt and black pepper. Stir together until dressing has emulsified. Add dressing to the orzo salad and toss to coat. Serve chilled or at room temperature.