When you say Mimosa, are you referring to the Silk tree with the pink flowers? There are a couple of ways to make a tincture out of it. For dried herbs, you want to have about four parts alcohol and one part herb, and with fresh herbs you need to have a two parts alcohol and one part fresh herb ratio because there is more water in fresh herb than dried herb.
If you are working with dried herb and bark, I see no reason why you can't break it down with a mortal and pestle before adding it to your alcohol.
By the way, a tincture can be made with 40 proof vodka, glycerin, or apple cider vinegar.
I hope that you found this useful!