Jalapeño Onion Smash Burgers (25 Min, 4 Servings) - Zest Plate

Ingredients

• 3 tablespoons mayonnaise
• 1 1/2 tablespoons ketchup
• 1 teaspoon Worcestershire sauce
• 1/2 teaspoon black pepper
• 1/4 teaspoon garlic powder
• 1/4 teaspoon kosher salt
• 680g high-quality 80% lean ground beef
• 1 teaspoon canola oil
• 1 large yellow onion, very thinly sliced (about 2 cups)
• 1 large jalapeño chile, very thinly sliced (about 1/2 cup)
• 1 1/4 teaspoons kosher salt, divided
• 3/4 teaspoon black pepper, divided
• 4 American cheese slices
• 4 soft hamburger buns, split and toasted