Pasta Verde

INGREDIENTS

• 1 pound gemelli, or other short pasta
• 2 tablespoons grainy mustard
• 2 tablespoons white-wine or sherry vinegar
• 1/4 cup plus 2 tablespoons extra-virgin olive oil
• Coarse salt and freshly ground pepper
• 1 sweet onion, halved lengthwise, then cut crosswise 1/4 inch thick
• 2 small zucchinis, halved lengthwise, then cut crosswise 1/4 inch thick
• 8 ounces snap peas, tough strings removed
• 3 ounces baby spinach, (or 1 bunch regular spinach, stems trimmed and leaves coarsely chopped)
• 1 small bunch scallions, thinly sliced (about 1/2 cup)
• 1/4 cup packed fresh basil leaves, cut into very thin strips