3 tablespoons ketchup
2 tablespoons canola mayonnaise
2 teaspoons sweet pickle relish
1 teaspoon Dijon mustard
1 pound ground sirloin
1/8 teaspoon salt
1/8 teaspoon freshly ground black pepper
Cooking spray
4 (1-ounce) slices reduced-fat, lower-sodium Swiss cheese (such as Alpine Lace)
4 green leaf lettuce leaves
4 (1 1/2-ounce) hamburger buns
4 (1/4-inch-thick) slices red onion
8 (1/4-inch-thick) slices tomato
1/2 ripe peeled avocado, cut into 1/8-inch-thick slices
8 bread-and-butter pickle chips