How to Make It
Prepare the Beef: Combine salt and paprika in a small dish; rub evenly over roast. Heat a large cast-iron skillet over medium for 5 minutes. Add oil. Place roast in hot oil; cook 10 minutes turning to brown all sides. Add stock, ketchup, and browned roast to a 6-quart Instant Pot. Cook on HIGH pressure according to manufacturer’s instructions for 35 minutes. Release pressure; cool 10 minutes. Transfer roast to a platter; shred meat, adding 1/2 cup cooking liquid to keep moist.
Prepare the Pickled Peppers: Heat vinegar, water, sugar, and salt in a small saucepan over high until boiling, about 5 minutes. Remove from heat. Place peppers in a shallow bowl; pour vinegar mixture over peppers. Let stand at least 15 minutes.
Assemble the Nachos: Arrange beet chips on a platter. Top with half of the quark. Scatter sauerkraut evenly over cheese, and top with half of the Beef. Top with Pickled Peppers, queso fresco, radishes, and dill. Top with remaining half Beef and quark; sprinkle with salt.
Quark can be found at Whole Foods and other specialty grocers. If you are unable to find it, you can substitute 1/2 cup of sour cream thinned with 1-2 tablespoons water.