Step 1

Spray cold grate of gas grill with grilling spray. Preheat grill for medium heat. Grill franks 5 to 7 minutes or until hot, turning occasionally. Remove from grill; keep warm.

Step 2

Whisk together vinegar, mustard, salt and pepper in medium bowl. Whisk in olive oil until well blended. Toss spinach and tomato with dressing.

Step 3

Slit franks lengthwise down centers; stuff each evenly with spinach salad. Serve immediately.