Combine chicken broth, barley, salt, and garlic in Instant Pot. Shut lid, set to sealing, and cook on High Pressure for 35-40 minutes. When done, either do a natural pressure release or a quick valve release. Rinse and drain barley.
Alternatively: combine chicken broth, salt, and garlic in a large saucepan on high heat on the stovetop. Bring to boil, add the barley, and reduce to simmer until liquid absorbed or barley is tender approximately 45-55 minutes.
Once the barley is cooked, mix in 1 tablespoon of lime juice, can of black beans (rinsed and drained), and chopped cilantro. Taste and add the second tablespoon of lime as desired.