1. Preheat the oven to 350 degrees . Line 24 mini muffin cups. In a large heat-proof bowl, combine chocolate and oil. Place bowl over a pot of simmering water and let stand until chocolate is melted. Stir until smooth; set aside.
2. Using an electric mixer set to medium speed, whip eggs and sugar until pale and thickened slightly, about 6 minutes. Using a rubber spatula, stir in chocolate mixture, vanilla extract, salt and flour until smooth. Spoon batter into prepared muffin cups, filling each three-quarters full. Bake until cakes are puffed up and set on top, 6 to 8 minutes (cakes will fall slightly as they cool).
3. Cool 5 minutes, then carefully remove cakes from muffin cups. Allow to cool completely, then dust with sifted confectioners' sugar.