I'm not sure, as I have never given tortoises hay, but I would think you could soak the hay in water until it's rehydrated. I'm probably going to dehydrate grass so in the winter time then I can rehydrate it, so I'm not limited to store bought greens.
How old is Sahara ?
When a sulcata tort is under a year old I would not try to feed hay. They need fresh greens and fresh gras for their growth.
When your sulcata is older you can try to feed hay. They older they get, their hunger and appetite develop and some day they will eat hay as a normal food.
All 3 of my little Torts (Sulcata, Leopard, Hermanns) get a mixture of ground up Timothy Hay & Orchard Grass, Rep-Cal Maintenance Formula Tortoise Food, Zoo Med Natural Grassland Tortoise Food, & Mazuri. All Mixed up and soaked into a scrumptious Mud. I use a small Coffee Grinder, kind of a pain but it gets the job done.
I sprinkle Organic Wheat Grass Powder, Cactus Powder, & TNT (Total Nutrition for Tortoises) on top as a bonus,
Here's Maximus (20 months old) chowing down as do my Hermanns & Leopard.
I've been doing this since they were all about 6 months old.
I accomplish this with two methods. You can use one or both.
1. Feed whatever food the tortoise is used to eating on a bed of grass hay. Over time start putting a few pieces of grass hay on top of the food, and eventually start mixing in some hay with the food.
2. Get a handful of grass hay and chop it up with scissors. Then, put your pile of chopped grass hay into some water for an hour and let it rehydrate. Next mix it all in with the tortoises favorite greens. Start with tiny tiny little amounts at first, like less than 1%. Just a few flecks. Gradually add more with each meal so that the tortoise slowly becomes accustomed to the smell, taste and texture of the grass. You can also used soaked ZooMed Tortoise Chow pellets in this same way.
This works best with bermuda grass hay or orchard grass hay. Timothy is too stemmy in my experience. You can use plain bailed hay like from a feed store that sells stuff for horses and live stock, or you can use the pellets of blended up hay. Just make sure the pellets you use are nothing but pure blended grass hay with no additives of any kind.
Eventually, you tortoise will just start eating the plain grass hay. Some take longer than others to get into it.