One of the ways we will likely have to feed ourselves post TEOTWAWKI is by cooking food in methods that are not the norm for us. If your stove top and oven are rendered out of commission, there will be a need to cook in other ways if you're going to cook at all. Depending on what's for dinner, it very well may be edible while cold. In the case of meats, however, cooking to the proper internal temperature is necessary for your health and well-being, so in that case, grill you must.
For hundreds of years, food has been prepared over an open flame. Cooking by fire has proven successful time and time again, and building a fire over which you can cook is an accomplishable task. Relying on this old standby is great, but what other methods are you willing to try? Fire is more of the common denominator of cooking rather than the one and only way. How you use fire is just as important as creating it in the first place. Incorporating a heat source with a rack of some sort elevated above it is pretty much the trick to a successful cooking area, which can be made in a variety of ways from many different types of materials.
For example, if you have skewered food, placing two thick branches over a heat source (fire!) that are close enough together to balance the skewers will work fine. Just be careful if you use bamboo as some of the chambers hold water which can be heated to become steam, which may then explode.
If you've got an old metal storage rack lying around, remove one of the shelves and place it over a flame. This will give you the elevated cooking surface you need to balance a pot or pan.
Although labor intensive, a log can be cut with a chain saw into segments that extend part way down it and stuffed with paper then ignited. This will give you a flat cooking surface but should be monitored to ensure embers are not smoldering deep inside when you are done.
A simple tin can could be cut down and wrapped with foil to create a basin in which charcoal or kindling can rest. Ignite and place a rack over the top and you're good to grill.
Ceramic pots for plants can also be used for cooking. Place charcoal or kindling in the bottom and ignite, then place a rack above the heat to prepare a warm meal.
In these options don't fix your little red wagon, then perhaps what you need to do is cook on your little red wagon. Place a layer of foil atop the wagon and add your heat source. Position bricks or flat stones on the side to elevate your cooking rack and let your wagon prepare dinner.
While some of these options are not the typical choice you might make, there is no reason they would not work in a pinch. Although you will come across survival ideas that are less than ideal, the entire concept of survival is based on less than ideal, so if that means cooking dinner over a little red wagon, then so be it. Adopting strange techniques and making them work is part of what survival is all about, and in the end, at least there will be a dinner to eat, even if it must be cooked by alternative means.