Bring a saucepan to medium heat. Add the olive oil and the minced onions. Sauté, stirring occasionally for 3-4 minutes or until the onions are soft. Add the garlic and cook for 1-2 more minutes without browning.
Add the canned black beans along with the liquid in the cans. Bring to a simmer and cook for 20 minutes.
Use the back of a slotted spoon or spatula to mash the beans in the saucepan. Season with salt and pepper, adjusting as needed to your taste.For a thicker consistency, cook the beans a few minutes longer. For a thinner consistency cook the beans a few minute less than 20 minutes.
Notes
Onion: Use half of a small yellow onion. Mince the onion so that it disappears as it cooks in the beans and only adds flavor rather than texture.
Black Beans: Look for canned beans that only contain beans, salt, and water. I choose Organic Black Beans from Whole Foods because the cans are made without a BPA lining.
Salt and Pepper: Amounts for each are given, but feel free to tailor the amounts to your taste preferences.