Part 4/8:
Place the cleaned portobello caps in a bowl, then pour the vinaigrette over them, ensuring they are generously coated. Use gloves during this process—your hands will get messy, but they'll also stay clean and the marinade will coat the mushrooms evenly.
Arrange the marinated mushrooms on a baking sheet and bake at 375°F (190°C). Baking time varies depending on mushroom size, generally around 15-20 minutes. Check their tenderness with a toothpick; they should be soft but not mushy. Larger mushrooms may take slightly longer, so testing is important to avoid over- or under-cooking.
Once cooked, allow the mushrooms to rest and release excess water, which prevents the final dish from becoming too soggy.