Braşovence Breaded Crepes With Mushroom Filling

Name: Braşovence (Breaded Crepes With Mushroom Filling)
Ingredients: Generous 1 ½ cups (7 oz/200 g) all-purpose flour; 2 eggs; 2¼ cups (550 ml) whole milk; 1 teaspoon salt; Vegetable oil or sunflower oil, for frying; 2 tablespoons vegetable oil or sunflower oil; 2 onions, finely chopped; 9 oz (250 g) mushrooms, finely chopped; Salt and freshly ground black pepper; 2 eggs, beaten; Generous ¾ cups (3½ oz/100 g) all-purpose flour; ¾ cup (3½ oz/100 g) breadcrumbs; Sour cream or plain yogurt (optional)