In large bowl, dissolve yeast in warm water. Let stand 5 minutes. Add salt,oil, oil or butter, and flour. Beat until dough is smooth and satiny. Cover, let rise for 1 hour (until doubled). Cut onions into thin slices. Place in frying pan along with ham and cook over low heat until onions are soft (about 15 minutes). Remove from heat, stir in sour cream, eggs, salt to taste, and caraway seeds. Butter 25 cm pie, quiche or tart pan. Preheat oven to 200ºC . On lightly floured board, roll out pastry to fir prepared pan. Turn filling into lined pan. Bake for 35 to 40 minutes until crust is browned and pie is set.