My hotel reception guy recommended El Remo for curadillo. When I asked about other restaurants/foods, he said Julio. There was no thought behind it, just straight answers. After the next couple of days I could see why. I never saw these two restaurants open at the same time - on Wednesday it was Casa Julio, Lonja, the surrounding places next to El Faro and places at the waterfront end. On Thursday is was El Remo, Opera and El Faro. I don't know if there's a system behind it or just the restaurant decision on the day (since for example El Remo said not open on Mondays other than festivals, but was closed on this Tuesday).
In any case Casa Julio and El Remo were always the busiest places. In particular Casa Julio was full for lunch and dinner. I suppose dinner that evening was helped by the Champions League showing (no Spanish team though) and some older guys standing around the bar watching. But the seated areas inside and outside were completely full with people waiting both lunch and dinner. That says something and it was all true.
The little place had a great cosy atmosphere. The staff are very friendly and helpful. My cider was served in a contraption that negated the need to pour from a great height and produced excessive fizz on demand.
I had a side serve of prawns with the cider for €6 (considering cider is €2.5 or so, that's an incredible bargain) compared to the full size prawn dish for €15. I couldn't quite understand if the prawns were bigger or just the serve was bigger in the main (I'm pretty sure the latter), but I'm sure I made the right decision for the cider bonus serve. The prawns were grilled with just a tiny amount of outside singeing but were cooked well inside and heavily salted/seasoned. I ate the whole lot, heads and all, and it was delicious.
I had read about, but wasn't overly interested in the mejillones picantes (since I can cook mussels easily myself) but thought I'd give them a try here as a cheap €8 extra dish to the prawns. I'm glad I did just to see. The mussel meat was reasonably large and the picante sauce is spicy without being very salty. It was good to eat with the basic half baguette served. Sadly half the mussels weren't debearded, but oddly the other half were. Go figure.
This would be my choice of place to eat in Cudillero if you want good simple seafood dishes.