Place the dry black beans in a large bowl and add enough water to cover the beans with at least 4 inches of water. Cover and let sit overnight.
When ready to cook the beans, transfer them along with their soaking water**** to a large pot, making sure that they are still covered with at least 2 inches of water; add more if necessary. Add the onions and garlic, but don't add the salt just yet.
Bring to a boil, then cover loosely and reduce the heat; simmer for about 25 to 30 minutes. After this time, add the salt and let your beans cook uncovered until they are completely tender and the liquid has thickened and reduced to a point that it just barely cover the beans. If too much liquid should evaporate during the cooking process, feel free to add more.
Remove from heat, adjust seasoning and allow your beans to cool completely.
Note that this recipe yield more cooked beans than needed to make a batch of gallo pinto, but trust me you'll be glad to have leftovers. The beans reheat and freeze really well, so you can either reheat and serve them with cooked white rice (you have cassado right there, another typical Costa Rican dish!) or freeze them and keep them to make another batch of gallo pinto later (or sooner!)
TO MAKE THE GALLO PINTO
Heat the olive oil in a large skillet or saute pan set over medium heat. Add the onion, garlic, bell pepper and thyme and cook until soft and fragrant, about 5 minutes.
Add the cooked beans in their cooking liquid (if using canned, add beans and liquid - do not drain), Salsa Lizano (or Worcestershire and cumin), and hot sauce if using. Stir to combine and simmer for a few minutes, until practically all the liquid is evaporated.
Add cooked rice, stir well until the rice is completely coated and continue cooking until heated through, about 3 minutes.
Remove from heat, fish out thyme sprigs and stir in chopped cilantro.
Serve immediately, garnished with a few lime wedges, if desired.
*Home cooked beans are always preferred, but if there was no time for that, you could always substitute one 19oz can of black beans and their liquid.**Salsa Lizano is said to be absolutely crucial to preserve the authenticity of the dish; if you leave it out, the flavor will simply not be typical. You should be able to find Salsa Lizano in specialty/ethnic food stores or online. However, if you were absolutely unable to get your hands on it, your best option would be to substitute Worcestershire sauce and add about 1/2 teaspoon of ground cumin to the dish.***This recipe works much better when using rice that’s had a chance to sit in the fridge for a while and chill completely; rice that’s freshly cooked and still warm will only go mushy on you, rather than give you the desired separate, chewy grains that you are after. If you didn’t have any day-old rice on hand but still badly wanted to make gallo pinto, do not despair… You could always cook some fresh, spread it across a baking sheet as soon as it’s ready and then flash-cool it in the freezer for about 30 minutes before using it.****I like to hold on to that soaking liquid as it gives the cooked beans a really rich, darker color, which then gets transferred to the rice in the finished dish. If you prefer to rinse your beans after they've soaked and start with fresh water, you can totally go ahead and do that. It's not going to change the flavor at all.