Heat the olive oil in a skillet over medium high heat, and saute the onion until it's softened, about 7 minutes. Add in the garlic, cumin, chili powder, and oregano, and stir for 1 more minute.
Add the drained beans to the pot, along with the water and salt. Bring the liquid to a boil, then lower the heat to a simmer and cover the pot. Cook until the beans are more tender, about 5 minutes.
Remove the lid and add the lime juice. Use a potato masher to mash the beans directly in the pot. You can make the refried beans as smooth, or leave as much texture as you'd like to.
For smoother beans, transfer them to a food processor and process briefly, until the texture is as smooth as you prefer. Adjust any seasoning to taste, then serve warm right away. Leftover refried beans can be stored in an airtight container in the fridge for up to 5 days.
Notes
Nutrition information is for roughly 1/2 cup of refried beans, assuming you end up with 3 cups from this recipe. This information is automatically calculated, and is just an estimate, not a guarantee.*For a smoky flavor, add a 1/2 teaspoon of smoked paprika along with the other spices.*When I don't feel like dicing an onion, I've also blended a 4-oz. can of diced green chilies in with the beans, and they are delicious that way, too. (In that case, you might not need the added lime juice or as much salt, since the canned chilies already contain some sodium.)