Turkish Borek with Cheese or Meat Filling

Ingredients

• 3 tablespoons vinegar
• 5 tablespoons oil for the dough, plus about 1/2 liter for submerging
• 1 and 1/2 teaspoons salt
• 2 cups water, room temperature
• about 1 kilogram flour
• plastic wrap
• 1 (500-gram) package Canaan cheese (cheese for baking)
• 1 cup grated 5% Bulgarian feta cheese
• 200 grams kashkaval cheese or Gouda, diced
• 2 eggs
• salt (if needed; taste before adding)
• chopped fresh spinach (optional) OR chopped green olives (optional)
• 50 grams butter, softened
• 1/3 cup milk
• 1/3 cup oil