Step 1

Prepare the barbecue for grilling (direct method) over high heat (230-290°C)

Step 2

Lightly brush the onion slices and tomatoes with olive oil. Brush the cooking grates clean. Grill the onion slices over a high heat for 10-12 minutes, with the lid closed as much as possible and turning once, until lightly charred on both sides. At the same time, grill the tomatoes over a high heat for 3-5 minutes, turning occasionally, until the skins are loosened and lightly charred on all sides. Set aside.

Step 3

Peel and discard the loosened skins from the tomatoes. Roughly chop the tomatoes and onions. Warm the olive oil in a large saucepan over a medium heat. Add the garlic and grilled onions and cook for 2 minutes, stirring occasionally. Add the grilled tomatoes, cannellini beans (with their liquid) and basil. Season with salt and pepper. Bring to the boil, and then simmer for 10 minutes, stirring occasionally. Adjust seasoning, if necessary. Add the balsamic vinegar, give the soup a final stir and serve.