Butterflying the pork increases the surface area to absorb the marinade, and the thinner meat cooks more quickly on the grill. Serve with grilled corn on the cob. This recipe will also be good in the fall since its flavors go well with butternut squash.
Slice tenderloins lengthwise, cutting to, but not through, other side. Open halves, laying tenderloins flat. Place tenderloins in a large zip-top plastic bag. Add 1/4 cup Maple-Balsamic Dressing; seal and shake to coat. Marinate in refrigerator 20 minutes or up to 8 hours, turning bag occasionally.
Prepare grill to medium-high heat.
Place the remaining 1/4 cup Maple-Balsamic Dressing in a small saucepan, and bring to a boil. Reduce heat, and simmer 2 minutes or until syrupy.
Remove tenderloins from marinade; discard marinade. Sprinkle tenderloins evenly with salt and black pepper. Place on a grill rack coated with cooking spray; grill 8 minutes on each side or until a thermometer registers 155° or until desired degree of doneness. Remove pork from grill; cover and let stand 5 minutes. Cut pork across grain into thin slices, and drizzle with reduced Maple-Balsamic Dressing.