Heat butter and 2 tbs oil in dutch oven over medium heat. Add about 5 pheasant pieces -- make sure everything's in a single layer and not overly crowded. Cook 3 minutes/side until brown and remove. Repeat with remaining pheasant, adding oil as needed.
Remove last batch of pheasant and set aside. Add mushrooms. Cook about 10 minutes, stirring often.
Add onions to mushrooms, cooking for three or four minutes until tender.
Add 2 tbsp of reserved seasoned flour. Stir well.
Add wine, stock, lemon juice, salt, and pepper. Bring to a simmer and make sure to scrape all those bits from the bottom of the dutch oven. Add pheasant pieces.