Mix the shallots and the vinegar in a bowl and marinate at room temperature for about 30 minutes to 1 hour.
Using a slotted spoon, take the shallots out and reserve them for later.
Add the onion powder, garlic powder, paprika and sugar to the vinegar, then add the olive oil in a thin stream and whisk well until the mixture emulsifies into a thick dressing.
In a larger bowl, combine the salad greens, peppers and reserved shallots, and dress with the dressing to your liking.
Place the salad in serving dishes and top with shaved provolone.