Burger Bar Toppings

Name: Burger Bar Toppings
Ingredients: 1/2 c. mayonnaise; 1/4 c. ketchup; 1/4 c. chopped cornichons; 2 tsp. yellow mustard; 2 tsp. prepared horseradish; 2 tsp. grated onion; 1 large onion; Oil; 1/4 c. steak sauce; 8 slices bacon; 2 tbsp. chives, snipped; 2 tbsp. flat-leaf parsley, chopped; 1 lemon zest; 2 peppers, quartered; 2 tbsp. olive oil; Kosher salt; Black pepper; 2 tbsp. sherry vinegar; 1 tsp. maple syrup; 1 clove garlic, smashed