Clean and sear the portobello mushrooms.
Prepare the mushroom filling by chopping and cooking the mushrooms with shallots, garlic, and seasonings.
Prepare the onions by caramelizing them with butter, sugar, and apple cider.
Roll out the puff pastry and assemble the Wellington with mushroom filling and caramelized onions.
Bake the Wellington until golden and flaky.
Optional: Prepare a port reduction sauce by cooking shallot, garlic, peppercorns, port, stock, and thyme.
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