To be efficient when making a donburi recipe like the ten don, it is good to start with steaming or cooking the rice first, because it is the ingredient that takes the most time to cook.
Allow the rice to cook in the rice cooker while you prepare the other ingredients. Cut the eggplant and renkon into 1cm-thick slices – this will ensure that they will get fried faster in the saucepan, then start removing the shell from the shrimps but leave the tail attached to their bodies.
Now, use a paper towel to pat the ingredients dry and put them in the fridge in order to be chilled. Chilling ingredients is the secret to a nice and crispy tempura batter.
Once the ingredients have been chilled in the fridge for a good amount of time, then use either a heavy bottom pan or a deep fat fryer to fry the ingredients to a delicious crisp. Adjust the temperature and make sure it’s between 160 - 180˚ Celsius (320 - 360˚ Fahrenheit) before you fry the ingredients, or if you’re using a deep fat fryer, then its regulator will take care of the heat automatically. Simply dropping a splash of batter into the oil should help you determine whether the oil is ready or not (the tempura batter will sizzle when the oil is hot enough).
Drizzle the ingredients with some flour before you dip them into the tempura batter (make sure that each one is covered completely), then deep fry them one by one for about 60 seconds (per side) until it changes into a golden color. Avoid placing more than 2 pieces of ingredients in the pan or deep fat fryer as this will lower the temperature of the oil to a less than ideal level. When all the tempura ingredients have been cooked, then remove them from the pan and place them on a wire rack to drain the excess oil, then lay them on a paper towel to dry them.