Preheat grill to medium-high heat. Place onions in a foil packet. Spray all other vegetables, lightly, with olive oil spray. Place vegetables in a grill pan or straight on the grate and grill until done (corn takes about 1o minutes to grill "naked"). Remove all vegetables from grill, except onions, and cook chicken at around 425-450F. Grill for 10 minutes, flipping once, or until internal temperature reaches 165 degrees F. Now assemble your bowls. Divide mixed greens, evenly, into 4 large bowls. Cut corn off the cob and divide among the 4 bowls. Top with black beans, grilled vegetables, pineapple and grilled chicken. In a blender, combine pineapple juice, olive oil, red wine vinegar, brown sugar and salt. Blend a few seconds and drizzle desired amount of pineapple vinaigrette over salads before serving. Top with toasted almonds.