Divide Greek dressing evenly among the 5 jars, forming the first layer. Divide tomato halves evenly among the jars, forming the next layer. Top the tomatoes with Kalamata olives and red onions.

Place 3 ounces of steak over the onions in each jar. Top steak with 2 cups romaine. Place 1/4 cup feta cheese over the romaine. Seal and refrigerate jars until ready to serve.

Divide croutons among 5 small resealable plastic bags.