To make Thousand Island salad dressing, prepare a paste from 1/2 clove of garlic and 1/4 teaspoon of kosher salt. Make the past by crushing the garlic and salt together with the side of a chef's knife until it is broken down and integrated.
Put the paste into a small mixing bowl and whisk in 3/4 cup of mayonnaise, 1/4 cup of bottled chili sauce and 2 tablespoons of ketchup. Also stir in 2 teaspoons of sweet pickle relish, 1 1/2 tablespoons of finely minced onion, and 1/2 a finely chopped hard-boiled egg. Mix everything together, and season with salt and pepper to taste. Serve the dressing immediately, or put it in a covered container, and store in the refrigerator for up to two days.
To prepare homemade mayonnaise for use in the dressing, combine 1 egg yolk and 1 tablespoon of Dijon mustard into the bowl of a food processor. Process until the mixture is fully combined, and then slowly add 1 1/3 cups of vegetable or canola oil in a thin stream while the mixer is still running. After the mix is completely combined, turn the processor off, add in 4 teaspoons of white vinegar or lemon juice, and pulse until smooth.