Step 1: Preheat grill to medium-high heat. Cut beef sirloin into 2.5 cm cubes. In a bowl, combine beef and shrimp with 2 tablespoons olive oil, dried oregano, minced garlic (half), salt, and pepper. Toss to coat evenly.

Step 2: Thread beef, shrimp, red onion wedges, and cherry tomatoes alternately onto skewers, ensuring even distribution and secure placement. Simultaneously, slice zucchini into 1 cm thick rounds, toss with 1 tablespoon olive oil, salt, and pepper.

Step 3: Bring a pot of salted water to a rolling boil for the orzo. Add orzo and cook according to package instructions until perfectly al dente (approximately 7-9 minutes). Drain immediately.

Step 4: Place skewers and zucchini on the preheated grill. Grill skewers for 3-4 minutes per side for beef (medium-rare to medium) and 2-3 minutes per side for shrimp, until cooked through and slightly charred. Grill zucchini for 2-3 minutes per side until tender-crisp with visible grill marks.

Step 5: While grilling, finely chop fresh parsley and remaining garlic. To the drained orzo, add the remaining olive oil, lemon juice, chopped parsley, and garlic. Toss vigorously to combine. Serve the grilled skewers and zucchini alongside the herbed orzo, arranging meticulously for an inviting presentation.