this is supposed to be a reference for people looking for information on food in Costa Rica:
traditional costa rican food is very heavy- rice and beans are served with everything and a lot is fried (plantains, meats, fish, eggs, etc.). Costa Rica is not known for its food, but there are ways to maximize the experience.
Your best bets for good food is to order seafood (usually fresh and local) and tropical fruits. The rainy and dry season have different fruits, but we (in the dry season) had a lot of pineapple, papaya and mango. Also some star fruit and passion fruit and a little guanabana, but that's mostly a rainy season fruit. Try the markets in every city for super-cheap fresh fruits and stay away from imported fruits like apples, which will not be as good and much more expensive.
Refrescos are like smoothies made with fruit juice, water and ice, or with milk instead of water. This was the best thing we had in Costa Rica. You can also get whole coconuts with straws to suck out the juice (not milk). Also, coffee was great at everywhere except some tourist places. Liquid yogurt and milk products were often good, especially in some of the smaller communities where the milk come delivered in metal cans from the mornings milking. Also in the smaller communities eggs are collected and distributed and are very fresh.
We stopped in at a couple of local bakeries and were mostly unimpressed by the puffy breads and sweets.