Brush each ear of corn with some of the Italian salad dressing; sprinkle each ear with chopped rosemary. Grill corn on the rack of an uncovered grill directly over medium to medium-hot coals for 20 minutes or until tender, turning often. Cool slightly. (Or, preheat oven to 425 degrees F. Bake brushed ears, in a shallow baking pan, for 30 minutes, turning once.)Advertisement
Cut each ear of corn crosswise into thirds. Set a 1-gallon sealable plastic bag in a large, shallow bowl; place corn and sliced tomatoes in bag. Pour remaining dressing over vegetables. Seal bag and let vegetables stand 20 minutes before serving, or chill for at least 4 hours or up to 24 hours, turning bag once or twice.
To serve, arrange spinach leaves on six chilled plates. Remove corn and tomatoes from bag with a slotted spoon, reserving dressing. Arrange corn and tomatoes on top of spinach. Pass the reserved dressing.