First caramalize the onions. Coat the bottom of a pan with oil. Heat the pan on medium-high heat until the oil is shimmering. Add the onion slices and stir to coat the onions with the oil. Spread the onions out evenly over the pan and let cook, stirring occasionally until caramalized.
Next, place the Tomato Braai Relish in a medium saucepan and bring to the boil. Add the sugar, parsley and chilli if using. Reduce the heat and simmer for 15 minutes or until the relish is thick.
Braai the boerie until cooked through.
Place each boerewors on a hot dog roll that has been lightly buttered. Top with the braai relish and onions and serve immediately with the skinny fries.