In a small skillet, heat 2 tbsp (30 mL) butter and oil over medium heat. Sauté onion for 5 minutes or until slightly golden. Add sage and garlic and sauté for 2 minutes more. Remove from heat.
In a large bowl, combine onion mixture, mashed potato and turkey. Mix well.
Pre-heat oven to 400°F (200°C)
Cut feta widthwise into ½-inch (1 cm) sticks. Mold approx. ¼ cup (60 mL) of the potato mixture around a feta stick to cover. Repeat until all ingredients are used.
In shallow dish, mix breadcrumbs with remaining 2 tbsp (30 mL) melted butter. Place flour and egg in separate shallow dishes. Roll croquettes in flour, then egg and finally in breadcrumb mixture to coat, lightly pressing crumbs on. Place on a baking sheet. Bake for 15 to 20 minutes or until golden.
Serve with cranberry sauce, turkey gravy or a dollop of sour cream.
*To make mashed potatoes, boil 3 large peeled yellow flesh potatoes until soft. Drain and mash with 2 tbsp (30 mL) butter and a dash of milk.
Tips: Use leftover or instant mashed potatoes for convenience.
Croquettes bake best if they rest in the refrigerator for one hour before baking.