I guess one primary decision you will need to make is to what extent you intend to provide supplemental
irrigation on the long term. Some will be necessary for just about everything in the establshment phase. Beyond that, a little research and observation around you
should come up with a list of likely contenders. Is your climate proper desert? (think date palm, mesquite, cacti, etc.) or is there
enough rain in the winter to call it Mediterranean? ( olive, fig, pistacio, pomegranate....) Other than plants
native to such climates, everything else will either require or hugely benefit (in terms of yield) from supplemental water, moist microclimate niches, etc.---even popular and common plants like citrus, avocado, and other fruits and nuts. On the other hand you mention clay soil, so beware of any spot where water stands for more than a few hours after a heavy rain....most food-producing plants don't like this and many will decline and die....sort of a catch-22.....I've ended up planting a lot of things on mounds and then running drip lines. If your site slopes at all, then swales, with the trees planted on the
berm, will help with both moisture and drainage......