Interesting - I think I used a little less ginger beer as I was using lowball glasses, but I quite liked how the spicy bite of the ginger played into the tequila, giving it almost a smoky sensation. I had to take a second to recall I did use tequila and not mezcal. Lime comes through, but the cassis flavor seems a mere accent - though it is likely also countering the tartness of the lime as well.