Preheat oven to 375F (190C).

In a large oven-safe skillet, saute the asparagus, mushrooms, red bell pepper, and beef pieces over medium heat until vegetables are tender.

In a separate bowl, whisk the eggs and fresh dill together.

Pour the egg mixture over the vegetables and beef in the skillet, ensuring an even layer.

Sprinkle the crumbled feta cheese evenly across the top of the frittata.

Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until the eggs are completely set and the edges are lightly golden.

Remove from the oven and let cool slightly. Slice and serve hot with roasted potatoes and a mixed greens and tomato salad.