3 leeks (white and light green parts), thinly sliced
4 green onions, sliced
3 large eggs
3 egg yolks
1 cup sour cream
1 tsp. dry mustard
1/2 tsp. each: salt and freshly ground black pepper
1 cup diced black forest ham
1/2 cup sun-dried tomatoes in oil, drained, sliced
Fit pastry into a 9-inch pie plate or 10-inch tart pan; flute edges. Sprinkle 1/4 cup Swiss cheese over bottom of pastry. Bake in a preheated 425°F oven 8 minutes or until golden brown.
Meanwhile, melt butter in a large skillet over medium heat. Add onion and leeks; cook, stirring frequently, 5 minutes. Add green onions; cook, stirring frequently, until onions are tender, 3 to 4 minutes. Set aside to cool for 10 minutes.
In a large bowl, beat together eggs, egg yolks, sour cream, mustard, salt and pepper. Reserve 1 tablespoon Swiss cheese. Stir remaining cheese and sun-dried tomatoes into egg mixture. Spoon onion mixture over bottom of baked pie shell. Spoon egg mixture over onions.
Place tart in a preheated 375°F oven; cover loosely with foil. Bake 20 minutes. Remove foil; continue baking 25 to 30 minutes or until center is set. Sprinkle reserved cheese over tart. Let stand 30 minutes before serving. Serve warm or at room temperature.