Balsamic Veggie Pasta

Bahan-bahan (6 porsi)

• 12 ounces uncooked pasta (I used penne)
• 3 tablespoons olive oil, divided
• 1 small red onion, peeled and thinly-sliced
• 1 pound asparagus, cut into bite-sized pieces (with ends trimmed off and discarded)
• 1 small head of broccoli florets, cut into bite-sized pieces
• 1 red bell pepper, cored and thinly-sliced
• Kosher salt and freshly-cracked black pepper
• 5 cloves garlic, peeled and minced
• 3 -4 tablespoons balsamic vinegar
• freshly-grated Parmesan cheese