Cook the frozen corn according to package directions for about 3-5 minutes. Drain and cool completely.

In a mixing bowl, combine the white onion, lime juice, olive oil, salt, black pepper, and cumin. Stir well and refrigerate for 15-20 minutes.

Finely dice the tomatoes and chop the cilantro. Rinse the black beans under cold water and drain thoroughly.

Add the diced tomatoes, black beans, corn, and cilantro to the dressing. Toss gently to mix.

Taste and adjust seasoning as needed. Chill in the refrigerator for at least 1 hour before serving.

Serve with tortilla chips or as a topping for tacos or grilled meats.