How to Make It
Make the short ribs: Sprinkle 1 tablespoon plus 1 1/2 teaspoons salt evenly over short ribs. Sprinkle rosemary, orange zest, juniper berries, and pepper on top of short ribs, pressing lightly to adhere. Place short ribs on a wire rack set inside a rimmed baking sheet. Chill, uncovered, 12 to 20 hours.
Remove short ribs from refrigerator. Let stand 30 minutes. Sprinkle with remaining 1 teaspoon salt.
Program a 6-quart programmable electric pressure cooker to sauté. Add olive oil, and heat until shimmering. Working in 3 batches, add short ribs to pressure cooker; cook, turning occasionally, until browned on all sides, about 20 minutes per batch (you will need to restart sauté function every 30 minutes). Transfer short ribs to a plate. Drain fat, reserving 2 tablespoons in cooker. Add onion, celery, and carrot to pressure cooker; cook, stirring occasionally, until softened, about 8 minutes. Stir in tomato paste, and cook, stirring constantly, until tomato paste coats vegetable mixture, about 1 minute. Add wine and vinegar; cook, stirring occasionally, until liquid almost evaporates, 8 to 10 minutes. Add stock and thyme sprigs; stir to combine. Return short ribs to cooker. Close and lock lid. Turn pressure release valve to sealing position.
Program pressure cooker to cook on manual on high pressure 45 minutes. Allow pressure cooker to release pressure (steam) “naturally” 10 minutes. Carefully turn pressure release valve to venting position to release remaining pressure from cooker until float valve drops. Carefully remove lid, and transfer ribs to a plate; set aside. Pour braising liquid through a fine wire-mesh strainer into a bowl; discard solids. Let strained liquid stand 5 minutes; skim off and discard fat. Transfer shorts ribs and strained braising liquid to a clean saucepan until ready to serve.
Make the apple salad: Toss together apple, sliced celery, dates, hazelnuts, olive oil, and salt in a bowl, gently separating dates with your hands.
Divide mashed potatoes evenly among 4 bowls; top each with 3 short ribs and about 3 tablespoons braising liquid (reserve remaining liquid for another use). Serve with apple salad.