Ingredients

• 3/4 cup vegetable oil
• 1/2 cup yellow onion, chopped
• 1/4 cup lemon juice (freshly squeezed)
• 1/2 cup celery, finely chopped
• 3 tablespoons mustard (try to find Creole mustard or other whole grain mustard)
• 3 tablespoons ketchup
• 4 tablespoons fresh flat-leaf parsley, chopped
• 2 tablespoons garlic, chopped
• 2 tablespoons prepared horseradish
• 1 teaspoon kosher salt
• 1/4-1/2 teaspoon cayenne (depending on how hot you like it)
• 1/4 teaspoon fresh ground black pepper
• 1/2 cup green onion, chopped (both green and white parts)