Cook pierogies according to package directions. Set aside.
In a large skillet and over medium-high heat, heat the oil and add the bratwurst meat (casing removed). Using two forks, break apart the bratwurst and cook until well browned, 8-10 minutes. *Optional to add 1/2 teaspoon hot pepper flakes to the browned sausage.
Add the cabbage and green onions to the skillet and cookdown until tender, 8-10 minutes.TIP: Use heat proof salad utensils and gently toss thecabbage to incorporate in the skillet. Add the pears, vinegar, and mustard. Cook for another 5 minutes. Season with salt and pepper.
Add the cooked pierogies to the hot cabbage and sausage mixture to warm them.
Serve in a bowl and top with chopped green onion and / or red pepper flakes.