In a saucepan, over medium heat, bring the beer up to a simmer. Add the sausages and cook until plump, about 4 to 6 minutes. Preheat the grill. In a saucepan, over medium heat, cook the potatoes in salted water until tender, about 15 minutes. Remove and drain well. Keep warm. In a sauté pan, over medium heat, cook the bacon until crispy. Add the onions. Season with black pepper. Sauté for 1 minute. Remove from the heat. In a large mixing bowl, combine the cooked potatoes, crispy bacon/onions with fat, vinegar, to taste, mustard, eggs, and green onions. Season with salt and pepper. Mix well. Using the back of a spoon, mash the mixture together. The salad should be well blended but with some lumps. Lightly brush the sausages with oil. Place on the grill and cook for a couple of minutes on each side. Remove the sausages from the grill. Mound the potato salad in the center of each serving plate. Lay the sausages next to the salad. Garnish with parsley. Serve with the brown bread and mustard.