In a large skillet, over medium-low heat, add 1/4 cup of oil and get the pan warm on the stovetop. Add the diced onion, garlic and corn kernels. Saute together until the corn feels cooked to the bite. Place in the oven until roasted (but not dried out) about 20 to 30 minutes.
For the mango salsa:
Combine the mango, onion, bell peppers, chives, lemon juice, honey, vinegar, salt, and pepper in a non-reactive bowl and chill.
For the vinaigrette:
Add, 1 at a time through the feed opening of a running blender, the vinegar, shallot, chives, salt and pepper. Leaving the blender running, add the oil in a slow thin stream and allow to emulsify. Taste and adjust seasoning with salt and pepper.
To make the tomato salsa:
Combine the tomato, tomatillos, garlic, parsley, and celery. Season, to taste, with salt and pepper and set aside.
Fold together corn mixture and black beans. Season with salt and pepper. Add enough red wine vinaigrette to coat. (Do not feel compelled to use all of the dressing.) Transfer to a serving dish, and top with a spoonful of mango salsa in the center surrounded by a ring of tomato salsa. Garnish with scallions and cilantro leaves. Serve with any extra dressing on the side.