- In a non-stick pan, roast the onion in olive oil at medium heat for 5 minutes, then lower the temperature and cook for an additional 15 minutes, stirring occasionally. Season with salt and cayenne pepper.
- Using a sandwich press, grill the bell peppers (lightly sprinkled with salt) for 20-30 minutes at medium heat.
- When the peppers are ready, put them aside and peel off the skin (it should come off easily - if it doesn't, let the peppers rest for 10 minutes in a sealed zip-lock while they are still warm).
- Grill the zucchini (also sprinkled with salt) for 10-15 minutes at medium heat.
- When the zucchini are ready, put them aside and roughly wipe the grill clean, while keeping it turned on.
- Assemble the sandwich by layering the cheese, the grilled vegetables, and the roasted onions.
- Warm up the sandwiches in the press until the cheese melts. Then add the fresh arugula and serve.
