Put the rice flour into a bowl and make a well in the centre.
Stir the sugar, water to ensure it has dissolved. Pour it into the flour and add the cold water. Combine to make a dough and knead for 5 minutes into a ball.
Dust your hands with some rice flour and shape the dough into 12 balls roughly the size of golf balls.
Holding a dough ball in one hand, use the thumb of the other and make a hole into the dough to form a cup. Press 2 pieces of chocolate, one on top of the other, into the hole and gather the edges of the dough to encase the chocolate completely. Do this with all the dough, then roll each of the balls in your hands until perfectly round, then roll them in sesame seeds.
In a double boiler or a heatproof bowl set over a pan of barely simmering water, break up the second bar of chocolate and stir with a wooden spoon until it starts to melt. Once melted do not stir again but leave it over the hot water until you are ready to serve.
Heat the oil in a deep-fat fryer or wok to 180°C/ 350°F/ Gas 4, or until a tiny piece of dough browns in 15 seconds. Be particularly careful if deep frying in a wok.
Deep fry the sesame seed balls, a few at a time, until the sesame seeds turn golden brown and the balls start to float to the surface, approximately 3-4 minutes.
Once cooked, place the sesame seed balls on a lined tray with kitchen paper to drain of excess oil while you cook the remainder. Serve warm, with the melted chocolate poured over. If you wish, you can cut open one of the balls on each serving and place a strawberry or cape gooseberry in the bed of chocolate.