Preheat oven to 400°F (200°C) fan bake. Line a baking sheet with parchment paper.
In a large bowl, combine ground lamb, red onion, garlic, egg, feta, mint, oregano, cumin, salt, and pepper. Mix well until combined.
1 lb ground lamb, 1/4 cup red onion, 2 garlic cloves, 1 egg, 1/4 cup feta cheese, 1 tbsp fresh mint, 2 tsp dried oregano, 1 tsp ground cumin, 1 tsp salt, 1/4 tsp ground black pepper
Cut puff pastry sheets into 4x4 inch (10x10 cm) pieces. Divide the lamb mixture into six portions and place one portion on a pastry sheet each. Place another suqare on top.
3 puff-pastry sheets
Bring two edges of the pastry squares together to form mini round wellingtons, pressing firmly to seal (check step-by-step instructions). Brush with egg yolk wash and sprinkle with sesame seeds.
1 egg yolk, 1 tsp sesame seeds
Place the wellingtons on the lined baking sheet. Bake for 20-25 minutes, or until the pastry is golden brown and puffed up. To measure well-done lamb, insert a meat thermometer into the thickest part of the pastry and ensure it reaches 160°F (71°C).
Let rest for a few minutes before serving. Serve hot with your favorite sides such as tzatziki or mint pesto.
Notes
Don't overfill: Too much filling will make it difficult to seal the pastry properly.Watch the salt: Some Greek feta cheeses are very salty. Taste it before adding the feta to the filling and reduce the salt if needed.Storage: You can assemble the wellingtons and chill them until ready to bake. Reheat lamb wellington loosely wrapped in foil at 300°F for 15-20 minutes, removing foil for the final 5 minutes to crisp the pastry.