Drain the black beans into a colander placed in the sink, rinse beans with cold water until no more foam appears, then let beans drain while preparing other ingredients.
In a small dish, stir together the lemon juice, white balsamic vinegar, Harissa, salt and pepper. Whisk in the olive oil, one tablespoon at a time.
In large bowl combine cubed avocado, mango, corn,peppers and onions.
Add drained black beans and stir very gently to combine. (Don't stir too much; you don’t want the avocado
or the beans to get crushed with the other ingredients.).