Meanwhile, cut the mushrooms in half or in quarters if they are very large. Slice the onions into thick half circles. Cut the bell pepper into 1-inch pieces, and slice the sausage into 1-inch pieces.
In a large bowl, combine the onion, bell pepper, mushrooms, olive oil, minced garlic cloves, fresh thyme salt, freshly ground black pepper and a mixture of dry herbs.
When the potatoes are halfway cooked, gently toss them with the mushroom and pepper mixture, along with the sausage.
Take out the searingly hot baking sheet from the oven and quickly spread everything out in one layer.
Roast in the preheated oven, uncovered, for 20-30 minutes, until the vegetables are all cooked through and golden brown, turning everything over halfway through cooking. You can broil the dish during the last few minutes of cooking to give it extra brownness and a slight char.
Garnish with fresh herbs, such as parsley, thyme, chives, dill, etc.
Make Ahead: Prep all the ingredients, without placing them onto the baking sheet. Store in the refrigerator up to 2 days. When you are ready to serve, preheat the oven with the rimmed baking sheet in it and then proceed with the rest of the steps.
Notes
You can use any cooked sausage that you like. I buy my sausage from a local Polish store, where they make their own sausage. It is SO delicious. The sausage that I used this time had a really smoky flavor, so it gave that same smoky flavor to the rest of the vegetables. However, you can use any kind of sausage that you prefer.
