Grilled Vegetable Salad

1/2 bunch asparagus, trimmed and cut into bite-size pieces

1 pint cherry tomatoes

1 medium red onion, cut into 1/2-inch rings

1 yellow bell pepper, quartered, seeds and ribs removed

1 red bell pepper, quartered, seeds and ribs removed

1/4 cup extra-virgin olive oil, for brushing

Salt and freshly ground black pepper

1/4 cup fresh basil leaves

1/4 pound feta cheese

Dressing:

1 medium clove garlic, chopped

1 tablespoon balsamic vinegar

3 tablespoons extra-virgin olive oil

Salt and freshly ground black pepper