In a bowl, mix all marinade ingredients. Add beef cubes, toss to coat, and marinate for 1 hour (or overnight for best flavour).
Alternate beef, peach slices, red pepper, and onion pieces on soaked wooden or metal skewers.
Cook over medium-high heat for 8–10 minutes, turning occasionally, until beef is nicely charred but still tender. Brush with leftover marinade during cooking.
Garnish with fresh coriander or mint. Serve with yellow rice, couscous, or a crunchy slaw.