Ingredients

• 1 small zucchini, halved lengthwise and cut into eight 1-inch slices
  
• 8 baby sunburst squash, halved or quartered, or 1 small yellow squash, halved lengthwise and cut into 8 1-inch slices
  
• 8 red boiling onions, halved, or 2 small red onions, cut into 8 wedges each
  
• 2 fresh ears sweet corn, husked, cleaned, and cut crosswise into 4 pieces each
  
• 1/3 cup butter, melted
  
• 1/4 teaspoon garlic powder
  
• 1/4 teaspoon onion powder
  
• 1/4 teaspoon ground chipotle chile powder or cayenne pepper
  
• 1/4 teaspoon dried oregano, crushed