I have a sloped walk up to stairs. I want to put steps on the slope. Screwing wood "wedges" into concred will give me the equivaltent of risers for the stairs, about 16" treads and 6" rise. Are tapcons the best way to anchor the "wedges", which are mahogany, about 15" long, starting at 5" and tapering to 0?
Yeah, I'd have to say Tapcons are about your only easy and plenty adequate choice. But, concrete's porous and holds moisture, so you'll only get about 30-years out of most fasteners. So, seal the concrete first. I only use Radonseal, it's very deep penetrating and permanent.
Although, I suspect you're introducing a differing stair height, which is not good and likely not legal...a lack of uniformity creates a trip-hazard. Stair over the existing stairs too and stretch everything out to a single long flight...steps of no more than 7" tall and no less than 10" deep.