We have been trying for months to get Elias to learn how to wash his hands in the sink, but he had some sort of mental block with it... He was actually afraid of it! Months ago, I bought him a little step stool to be able to stand at the sink, and he screamed in terror the first few times I tried to get him to stand on it. Oooooooook, guess you're not ready. So I just put it away for a while. Then when we moved into our new house in June, I just put the stool out in his bathroom so he could get used to it being there, and eventually it just clicked. Now he suddenly loves the thing and can't get enough of standing at the sink and washing his hands!
He hasn't figured out how to actually wash them yet, but he can turn the water on and off, rub his hands together after I put soap on them, and dry them on a towel. Still struggling with getting soap and then rinsing it off. And he generally only wants to wash his right hand, so I have to force his left hand in there too. But we're definitely making progress!
We're kind of trying the same approach with the potty as with the stool. We just have his potty seat next to the toilet, and occasionally we look at it. He knows how to put it on the toilet and take it back off again. And once he even sat on it fully clothed! I was just excited he sat on it and wasn't freaked out! I'm not at all in a rush with the potty training process, so I figure slow and steady will win this race. :)