Well that confuses things - for me at least!
The dark head and bib with a pale rest of the body would point to STE, but I think I can see dark carpal patches on both wings - which STE don't have.
RLB can have both features (see plate 384 in Forsman, Raptors of Europe and the ME for example), but it would be WAY out of range in Tenerife I think. I'm not familiar with Long-legged which I think would be more likely there, and I cannot find any similar photos online or in Forsman's books (although I've not looked far as dinner beckons!).
Unless someone else contributes I think you'll have to go with 'probable STE', and assume those carpal patches are shadows/photographic effects.
Mick