Step 1: In a small bowl, combine the mayonnaise, chipotle chiles, adobo sauce, and cilantro. Stir to blend and set aside. (Refrigerate if not using soon.)

Step 2: Set up the grill for direct grilling and preheat to high. Brush and oil the grill grate. Grill the poblanos for 4 to 6 minutes, turning with tongs as needed, until the skin is blistered and charred. Transfer to a cutting board and let cool. Scrape off the skin and remove the stems and seeds. Cut each poblano in half.

Step 3: Brush the onion slices with olive oil. Season both sides of each slice with salt and pepper. Grill the onions until darkly browned, 3 to 4 minutes per side.

Step 4: Slice a deep pocket in each steak through the side. (Be careful not to cut all the way through.) Spread a spoonful of the chipotle sauce in the pocket. Transfer the remainder of the sauce to a small serving bowl. Insert a piece of poblano, a slice of onion, and one-fourth of the provolone. Rub the outside of each stuffed steak with extra virgin olive oil and season generously with salt and pepper.

Step 5: Grill for 4 to 5 minutes per side, or until the steak is done to your liking and the cheese is melted. Place each filet mignon on a slice of grilled garlic bread. Spoon the remaining chipotle sauce.