To be honest, I don't have that much fun in playing around with the recipe, but I found this one and it just works for me: https://github.com/xil-se/FreeMate

But nowadays I just drink plain yerba mate with a splash of lemon juice, no added sugar. I do the FreeMate in summer a bit.

Edit: Btw, if anyone of you bought yerba mate before and thought it didn't taste great, for me personally there are huge differences between them. I like the milder ones a lot more that don't have much powder. If you have been disappointed before maybe try again with a different brand and don't forget the splash of lemon juice, that makes a crazy big difference