Since I was diagnosed with pre-diabetes back in July when I was hospitalized with a zombie bite , I’ve been fairly diligent in sticking to a low-carb diet. My blood sugar levels have dropped to nearly normal levels in the last couple of weeks - this is probably due as much to the fact that my body is no longer having to fight infection, as much as the low-carb eating and medication I’m taking. Still, I think that sticking to the low-carb is helping.
I have loosened up a bit on the carbs - I’ve added back some rice, whole wheat pasta and so on, and the blood sugar is holding steady. Still, I am staying away from bread as much as possible, since for some reason bread makes me blood sugar spike more than rice. I don’t miss it as much as I thought I would, but I do get a yearning for a simple sandwich now and then.
I saw this method for making sandwich ‘bread’ in a Japanese low-carb cookbook  for diabetics. It’s basically to use deep fried kouya or koya tofu (dofu) , or freeze dried tofu, as the ‘bread’. I’ve tried this out a couple of times, modifying the original recipe - I shallow fry it rather than deep frying it for example, and use regular vegetable stock rather than dashi. Note that the method is similar to the fried frozen tofu nuggets .
I’ve already written in much detail about koya tofu or kouya dofu a while ago on Just Hungry . It’s freeze dried tofu. If you can get a hold of it, it’s a really handy thing to have in your pantry. Look for kouya dofu at Japanese grocery stores - general Asian or Chinese stores and Korean grocery stores may not have it (though Korean stores are worth a try). Here’s a package that I bought from Japan Centre  by mailorder. These are about 3 inches (8cm) square when dried. If you can only find small ‘soup’ sized kouya dofu, you can turn them into mini-sandwiches, but do try to find the bigger squares, which will end up really looking like sandwiches.
Soak the dried kouya dofu in plenty of cold water. They will turn soft in 5-10 minutes, depending on the brand. If you squeeze the middle and no longer feel any hard core, they are ready.
Here are a couple that have been soaked and squeezed out.
Bring up a pot of vegetable soup stock or dashi stock to a boil. It’s fine to use soup stock cubes or granules for this, though homemad stock would be better. I usually just use a stock cube. Drop the kouya dofu in, and simmer them for a few minutes. Drain well and press lightly to get rid of excess moisture. (Sorry, I for got to take a photo of this step…)
Heat up a frying pan with olive oil or butter. Fry the kouya dofu on both sides until golden brown and crispy. (The original recipe called for deep frying, but I’ve just shallow fried them to cut down a bit on the fat.)
Drain the fried kouya dofu, and pat the surface with kitchen paper towels to get rid of excess surface oil. Cut the tofu in half horizontally, to end up with two ‘slices. Here you see one tofu that’s been cut in half, and another that’s still whole.
And here’s a simple cucumber and ham sandwich made with the halved ‘bread’. I put a little mayonnaise on the inside too. It tastes surprisingly good - not really like bread, but you get the feel of a sandwich. And it’s about as low-carb as you can get, as long as you watch what you put inside!
Calorie-wise, the ‘bread’ for one sandwich is around 160 calories, depending on how much oil or butter you use. Butter tastes better than oil…but oil is healthier of course. (Note, I did try toasting them in a toaster oven, and they didn’t get as nicely golden brown on the outside. I might try spreading them lightly with butter and toasting them though.)
I did try making the ‘bread’ without simmering the kouya dofu in stock - frying the soaked and pressed out tofu directly. That works, though the ‘bread’ is very bland. It also tastes a lot more greasy than the simmered version for some reason. If you want to fill it with a sweet filling (good for gluten-free people, a no-no for low-carbers) like peanut butter and jelly, you might try the non-simmered version, and blot off the surface oil as much as possible.
It just occured to me that kouya dofu might form an interesting base for low-carb french toast! I’ll try that sometime and report back.
You can make these the night before and cut them in half, ready to be formed into sandwiches. They do get soft after a while though.
The texture of regular, frozen tofu as I explained how to make here  is a lot moister than freeze-dried tofu, and so not as bread-like. You can give it a try if you like of course, but I prefer to just make those cutlets or fried nuggets from frozen regular tofu.