So we're both taking our first bite of steak and simultaneously going "oh, so this is what grass fed is supposed to be about"
La Castilleria, nominally a restaurant but actually a steakhouse, specializes in breed, locale and age specific beef and is probably most correctly used for the first time by ordering one steak from a 4-6 year old cow of the very local retinto - a red haired breeed which you can see walking all around Cadiz province, and which if you're lucky has been grazing near the coast, obtaining some pré-salé like traits and a second from a 9-11 year old vaca rubia from Galicia. The first is aged for just long enough to obtain good texture (2 weeks?) while the second is aged for over 45 days. The first is going to be the best grass fed steak you're likely to have had, the second will be very good in its genre (and I'm probably underrating it due to having had some of the best recently). Very decent wine list, order some appetizers for while the steak cooks but don't expect too much.
p.s. to put things in perspective, the two steaks (I think they were around 12-14 oz each, boneless) were 24 and 30 euros respectively.
eta: the restaurant is located in bumfuck-de-la-frontera