- Preheat a barbecue or griddle pan to a medium-high heat.
- Combine the oil, lemon juice, oregano, salt, and pepper, stirring until mixed.
- Slide a courgette slice down one of the skewers, followed by pieces of mushroom, red onion, and peppers, repeating until there is just a 3cm gap remaining at the top of the skewer.
- Repeat using the remaining skewers and vegetables. Brush each skewer liberally with the oil mixture.
- Cook the skewers for 12-18 minutes with the lid closed, flipping halfway.