Step 1Peel the potatoes and cut them into 3/4-inch cubes. Place them with the whole garlic cloves and onion in a medium pot.
Step 2Combine the water, soy sauce and sugar, stirring until the sugar dissolves. Bring to a boil. Reduce the heat, cover partially and simmer until the liquid starts to evaporate and the potatoes start to brown. Continue cooking until the liquid is reduced and thick. Do not overcook or over-stir the potatoes or they will lose their shape. Remove the pot from the heat while the potatoes are still slightly hard; they will continue to cook away from the heat.
Step 3Serve warm or chilled.