In a thick-bottomed pot mix pork belly, water, salt, oregano, pepper and bitter orange juice.
Cook uncovered over medium heat until all the liquid has evaporated (there will be some fat from the pork).
Switch the meat to another dutch oven (leaving seasonings behind), add oil and fry covered (to avoid splatters, see note) until it has turned a dark golden brown and skin is crispy.
Remove it from the heat and place it on a paper towel, let it cool down to room temperature.
Cut into small cubes (2 inches [5 cm]). Serve with tostones, garnish with lime wedges.
I want to repeat just how important it is to avoid hot oil splatters. When it's frying the oil gets pretty "explosive" so be very careful when uncovering the pot in which you fry it. It's best to use a splatter guard (link to affiliate store) or glass lid (with a hole to let the steam out) so you can see how things are going without uncovering. Remove from the heat before removing the lid to let the oil cool down a bit.