Campbell's condensed tomato, 1 can, straight from the can. Given the era of the recipe, I'm pretty sure that's what they meant.

And that's the magic part, right? It doesn't taste like tomato. It tastes kind of like the intersection of brownies, gingerbread, and carrot cake.

Plus you get science fair volcano action when you add the baking soda to the tomato soup while it's still in the can so while that's absolutely a valid shortcut I suggest doing it over the bowl. ^_^