Make a grilled cheese sandwich with your favorite bread and cheese. Once golden and melted, transfer it to a cutting board and let it cool completely.
Heat the Soup
Heat the tomato soup until piping hot, then transfer it to a preheated thermos and close the lid.
Pack for Lunch
Once the grilled cheese has cooled, cut it vertically into 3 or 4 sticks. Pack the dippers in a sandwich container and the warm soup separately in the thermos.
Notes
Don't pack the grilled cheese while it's hot. Steam creates condensation inside the container, which will make the bread soggy. Letting it cool completely before packing is the key to keeping the dippers crisp.