Costa Rican cuisine can be described as simple but wholesome. The spiciness often associated with Latin America has typically originated in Mexico, most Costa Rican foods are not spicy, but, as they simmer in a large pot, the flavors are blended.
Gallo pinto is a mixture of rice and beans with a little cilantro or onion thrown in. While more common at breakfast, it can also be served at lunch or dinner.
Casado, which means married, is the typical lunch in Costa Rica, containing rice and beans with meat, chicken or fish, always served with salad and fried plantain.
Plato del dia, is the 'Plate of the Day' and is often a Casado, but has the meat or fish selection of the day. Usually around 5.00 USD and includes a natural juice.
Good, fresh fruit is abundant in variety and low in cost. Mercados provide an excellent place to sample fruit and other Costa Rican fare, with many including sit-down snack bars. You are encouraged to experiment because some of the local fruits do not "travel well" as they are bruised easily and or have a short shelf life. The mango found in store in North America are much more fibrous and less sweet than the mangos found in Costa Rica. The fingerling bananas are much more creamy and less tart than the ones found in North America.
Be sure to stop off at a rest stop along any of the roads: a Casado and beer will cost ~USD3.
Don't forget to try the Salsa Lizano that you will surely find at any restaurant. It is a mild vegetable sauce that has a hint of curry and is slightly sweet. It's often referred to as Costa Rican ketchup. It tastes good on just about anything! Bring some home with you! You can find smaller sized bottles at any market.
Also as per usual in Central America standard breakfast fare is a ham sandwich, so people averse to eating pork might be advised to check out a grocery market for something else. Many Ticos will go to a local bakery and buy a loaf of white bread.
Vegetarians will find it surprisingly easy to eat well in Costa Rica. There are several International cuisine options also. In addition to American style food, Italian, Mexican, Peruvian and Indian are also available. Indian food generally has vegetarian, vegan and gluten free dishes. Try Indian Naans & Curries dishes. They taste better in Costa Rica because of natural ingredients.
Don't forget to tip tour guides, drivers, bellboys and maids. Restaurant bills include a 10% gratuity but leave an extra tip for good service. North Americans often get better service because they are used to tipping separately, but it's not necessary.
The beef cattle are raised on grass; the meat will taste differently from corn fed cattle. The cuts of meat at the local restaurants are also different. The taste of chicken is not discernibly distinct.