Let the soybean milk's temperature come to 70-80 degree. Meanwhile, grind the tatri and soak it in 1 table spoon luke warm water. Mix the citric water with soybean milk and stir 1-2 times. Do not stir continuously. Within 15-20 minutes the milk will coagulate and you will be able to see water separating from it. Once the milk and the water separates, spread a clean cloth over a strainer and pour the milk over it. Tofu will get collected on the cloth and the water will strain down into the bowl. Tight squeeze the cloth after folding it from both the ends and then place a hevay object at the corner to strain any excess water from the tofu.