Add potatoes, vinegar and a pinch of salt to a large pot and cover with cold water. Bring to a boil over high heat and cook until potatoes are just tender, about 10 minutes. Drain potatoes and transfer to a sheet tray lined with a clean dish towel to dry slightly.
Add enough oil to coat the bottom of a large skillet and heat over medium heat. Add the onion and cook, stirring until just translucent, about 5 minutes. Increase the heat to medium-high and add the cooked potatoes. Cook, stirring frequently, until the potatoes start to get crispy and golden brown on all sides, about 5 minutes. Add half the Spicy Corn Relish and continue to cook and stir until everything is incorporated and hot.
Remove from heat and top with fried eggs, sliced avocado, and the remaining Spicy Corn Relish. Serve hot.