I saw a recipe that employed Tomato Flour - how do you turn tomatoes into flour?
I don't think you'd be able to produce the same result at home. Even if the tomatoes could be dehydrated to the point where they are crisp enough to be ground, I don't think you could pulverize them fine enough very easily. Even if it is possible, the trouble wouldn't outweigh simply purchasing the commercial product.
I do this at home frequently; start by thinly slicing your tomato (roma tomatoes work best, because they're much meatier) and drying. You can do this using a food dehydrator, or in an open oven with low heat. This will take 5-10 hours, depending upon your tomatoes.
After your tomato slices are dried COMPLETELY, place them on a cookie sheet and freeze them. This will remove any remaining moisture.
Take your frozen and dried tomato slices and put small batches in a coffee grinder until they are powdered. If you want to ensure that there are no flakes, sift the powder through a flour sifter.
Hope this helps!
The tomatoes that I dry in my dehydrator are easily dry enough to grind to a powder in my food processor. I remove the seeds but not the skin before I dry them. It would be impossible to remove the seeds after they are dried as they are cemented into the fruit at that point.
I've seen Tomato Powder, but never Tomato Flour, I guess it could be a regional thing.
It's basically just dried tomatoes that are finely ground, as best I can tell, but I'd stem and seed them after they've been dried, as that's not going to contribute to the flavor.