Set Masterbuilt Gravity Series to 450° F.
Grill your bell peppers on all sides, making sure the skin is blistered and blackened.
Once blackened, add your bell pepper to a zip lock bag and allow them to steam for 30 minutes.
After 30 minutes, remove peppers from the bag and use a dry paper towel to rub the burnt skin off the peppers.
Slice peppers in 1-inch strips.
Add peppers to a small bowl with thyme, crushed garlic, salt, pepper, bay leaf, olive oil and red wine vinegar and allow to marinate for 1 hour, or up to 48 hours in the fridge.
Season flank steak with salt and pepper and grill until internal temperature reaches 130° F.
Allow to rest fully and slice thinly across the grain.
Match up 1 slice of steak with one slice of roasted pepper and roll into a spiral using a toothpick to hold in place.
Mix Greek yogurt with chopped thyme, black pepper, lemon juice and French onion mix.