When I was looking on the boards for places to eat in Manuel Antonio and surrounds and Monteverde I found little info. I am posting this to help future travelers, especially if traveling on a budget.
The Chicken Lady
There is a woman (there is also a man who has a different shed selling the same thing, we only went to a woman) who occupies a lean-to just outside of Manuel Antonio Park. Her shed sits among the tourist chotchky tents just outside of the park, between the road and the beach. For about $3.00 US you can get an entire chicken leg (thigh and drummy), beans, rice, and whatever salad she has made for the day and a cold Imperial.
Her food is simple and delicious. The chicken is cooked on a grill made from an oil drum and a grate. The chicken is nicely charred on the outside without tasting burnt and is moist and juicy on the inside. It is a communal style eating area so if you are not in to the outdoor eating experience this isn't for you. We went to the "Chicken Lady" 2 days in a row it was such solid food. As other posters have noted, Tico food is not spicy, fancy, or frilly, but this was just down home good.
Our perfect lunch was made more perfect when a quick cloud burst provided us a way to wash our hands. Perfect beach food! YUM!
Sophia's in Monteverde
There are a few upscale restaurants in this area. We wanted a nicer restaurant to celebrate our recent engagement. We had heard several people mention Sophia's, which touts itself and Neuvo Latino. That discription is what made me nervous, but we went ahead and tried it anyway.
As with other most of the other food we had it was lovingly prepared, and delicious. The dish that stood out to me was a corn and pumpkin soup that I had as an appetizer. It came with a cilantro crema. The two meat dishes were just ok, and very expensive compared to other meals we had there. Also, the dessert we had was incredible...banana bread pudding. It was very rich, so we were glad that we split it...
All in all the atmosphere, service, and food at Sophia's made for a nice upscale, but still casual dinner after a day playing in the Cloudforest. I would assume that during the high season you would definitely need to make a reservation, but it was not full when we went.
One more shout-out to Fad Yud Pollo de la Lena in San Jose. Great and cheap rotiserie chicken plates. Run by Chinese (I think) Costa Ricans who were very nice and friendly.
Hope this helps future travelers!