Preheat oven to 400º. In a large frying pan over medium-high heat, cook bacon until brown and crisp, about 7 minutes. Transfer to paper towels to drain. Pour off all but 1 tbsp. grease.
Reduce heat to medium, add onions, and cook, stirring occasionally, until translucent, about 5 minutes. Add garlic, allspice, and juniper and cook 2 minutes. Sprinkle in flour and stir to combine. Add beer and sugar and cook, stirring occasionally, until liquid is absorbed and onions are very tender, about 20 minutes.
Heat a medium ovenproof heavy-bottomed frying pan over high heat. Season steaks with salt and pepper and add to pan. Cook, turning once, until browned on both sides, about 3 minutes total. Transfer pan to oven and cook about 5 minutes (for medium-rare). Stir parsley and bacon into onions and serve over steak.
Note: Nutritional analysis is per serving.