You can use canned black beans for this (you can even use frozen corn), but the salad is best with beans that have been cooked, with good spices, until tender but not mushy.
Put the oil in a large nonstick skillet and turn the heat to high. Add the corn, along with a large pinch of salt and some pepper, and cook, shaking the pan or stirring occasionally, until the corn is lightly charred, 5 to 10 minutes. Add the garlic and cook for 1 minute more, stirring.
Combine the corn with all the remaining ingredients. Taste and adjust the s