Caramelized onion quiche

I have a great weakness for tarts. I’m always taken in by its crispy crust and delicate filling. This one in my opinion is perfect for an autumn-winter meal.
Besides, I just love caramelized onion!

Ingredients
Crust:
250 g (9 oz) wheat flour
¼ cup room temp. milk
¼ cup room temp. water
1 tbsp sunflower oil
1 egg
½ teaspoon salt
3 g dry yeast
filling:
2 eggs
2 medium onions
¾ cup grind cheese ( I used Old Ramdamer)
about 5 slices of ham or beacon ( I used tenderloin)
1 tbsp oil
6 tbsp thick sour cream
2 tbsp balsamic vinegar
½ teaspoon thyme
salt, pepper

Method
Mix flour with dry yeast and the rest of ingredients. Knead the dough until smooth and elastic, add oil. Form a ball, put aside in a bowl covered with tea towel, put it in a warm place until double sized (about 1 hour).
In a meantime, slice onion (slices 1-1,5 cm/ 0,5 in). Heat the oil in a pan and fry the onion rings both sides, sprinkle with thyme. Put the rings on a plate and spread the vinegar on them. Chop ham and fry it. Mix cream with cheese and ham, season with salt and pepper.
Grease tart pan and put rolled out dough in it. Spoon the cream mixture, put onion rings on top.
Bake at 180 oC (360 F), for about 30 min, until crust is golden.