Combine olive oil and balsamic vinegar in a dish large enough for the chicken. Prep chicken breasts: remove the tenders, and slice into the thickest part of the breast, opening it up like a book. Set chicken breasts and tenders into the prepared dish and marinate for 15–30 minutes.

Heat grill to 400°. Prep vegetables: spray lightly with olive oil and season with salt and freshly ground pepper to taste. 

In a small bowl, combine the grainy mustard dressing ingredients.

Cook penne according to directions, drain and place into your final serving bowl. Add a few tbsp of the dressing to keep it from sticking while you prep the remaining ingredients.

Grill vegetables to desired tenderness. If you're in a hurry, grill the red peppers lightly so you can leave the skins on and simple dice and serve. If you have a bit more time and prefer to roast them fully, blister the skin so that you can more easily remove it before chopping and adding to the pasta. When the vegetables are cooked, chop them up and add them to the pasta. (Discard the green onion ends, and just adding the chopped roasted bulbs)

Lightly oil the grill; place the balsamic chicken breasts and tenders onto the hot grill. After 2 minutes, reduce heat to 350°. The tenders will cook more quickly, check them after about 8 minutes and remove when cooked through. Continue cooking the breasts an additional 5–6 minutes until cooked. Remove to a cutting board and chop, adding to the pasta bowl.

Add remaining dressing to the pasta bowl, season with additional salt and freshly ground pepper to taste if needed. Divide among serving plates, and top with crumbled feta.