Corn and black bean salad with chipotle dressing - chinese grandma

Ingredients

• 5 ears corn (4-5 cups kernels)
• 1/4-1/2 cup diced onion
• 1 can black beans, rinsed and drained
• 1 bell pepper, any color, diced
• 1 pint grape tomatoes, halved
• 1 large avocado, diced (add just before serving)
• Optional: chopped cilantro or scallions
• 3/4 teaspoon salt (may need more depending on your salt and the salt content of your beans)
• 3/4 teaspoon black pepper
• 3 T extra-virgin olive oil
• 3 T red or white wine vinegar
• 1 T sauce from a can of chipotle peppers in adobo