The only thing I don't like about Sam's Yams is the price. $12-14USD for a bag of the big ones that nominally contains a pound, but doesn't seem to have all that many yam chews in it. So I've determined to make my own.
I'm no expert; I've only done this 4 or 5 times, but here is my current Charlie-approved recipe. It uses a food dehydrator, but if you're willing to set your oven on low and leave it on a long time, that should work fine too. My first couple of batches were done with an oven.
Step 1. Get a bunch of yams, a cutting board, and a sharp knife. I go for the really big yams because Charlie is a big dog and I want them to be like chews. If your dog is smaller, you might want to use smaller yams.
Step 2. Wash the yams and make sure the dog approves their quality. Note: make the dog give the yams back.
Note 2: make sure the dog stays back while you cut the yams.
Step 3. cut a smallish slice off one side of the yam. This creates a flat solid base, so the yam won't roll around as you slice it.
Step 4. Place the yam on the flat side you created and start slicing. I make slices between 1/2" - 3/4" (i.e. about 1.5 cm) thick. Note that the bigger and thicker the slices, the longer it will take to dehydrate them.
Be really careful during this step - yams are pretty hard & it takes some force to slice them. It helps if your knife is thin and sharp.
Step 5. Blanch the yams as follows. Arrange the slices on a microwave-safe plate.
Microwave on full power long enough so that the yams smell good and are a little soft. I think it would be ok to do less, but I zap them about 4 minutes on one side, then flip and do the same on the other side.
Remember: quality approval at every step!
Note: in future I plan to try using a fork at this stage to perforate the slices, as I think it would speed up the dehydration step.Step 6. Place the yams on a dehydrator tray. (Alternatively you could put them on a cooling rack to put in the oven.)
Arrange the slices so there's good airspace between them.
Step 7. Set the dehydrator (or oven) to 140' F (I think that's 60' C) and dehydrate for 10-20 hrs. After 10 hrs, start checking the yams and remove slices as they become dry. (The dehydrator manual says you know they're dry enough when you rip a slice & don't see beads of moisture form). Some of these slices were ready after 10 hrs, some took a lot longer.
When they're done, they'll look leathery like this but still be pliable. The smaller end slices usually curl up.
Final Step: Test the product
Charlie's not what you'd call a picky eater, but he says they're GRRRRRRRRRRRRREAT!!
