Preheat the grill to high heat.

In a small bowl, mix together the butter and garlic until well combined. Rub the mixture onto each side of the steak and season with salt and pepper.

Place the onion rounds, capsicum strips, and broccoli florets in a large bowl. Drizzle with olive oil and toss to coat evenly. Sprinkle generously with salt and pepper.

Grill the steaks for 4-5 minutes per side or until desired doneness is reached (65°C for medium rare). Transfer the steaks to a plate; cover loosely with foil to keep warm while you grill the vegetables.

Place the vegetables on the preheated grill grates; cook covered, turning occasionally, until lightly charred and tender-crisp, 8-10 minutes total depending on your preference of doneness.

Serve the steaks alongside the grilled vegetables, and enjoy!