Preheat oven to 250 degrees F. Season pork with salt and pepper on both sides. Heat a non-stick pan over medium heat. Add the pork and cook, turning once, until golden brown and cooked through, about 2 to 3 minutes per side. Remove to an oven proof platter. Hold warm in oven while you prepare sauce.
Add onions to pork pan and cook, stirring often until slightly softened, about 3 to 4 minutes. Increase heat to high, add cider, cider vinegar, sugar, chili flakes, and cinnamon stick. Bring to a boil. Add apricots and prunes. Reduce to a simmer. Add cranberries, apples, and swiss chard and cook until sauce is slightly thickened and chard and apples are tender, about 3 to 5 minutes. Add orange zest and cook 1 minute more.
Divide pork among serving plates, pour chutney over pork slices. Serve immediately.