Steps

1. Finely chop 1/4 onion.
   🕒 01:23
2. Place the chopped onion in a bowl, cover with plastic wrap, and microwave.
   🕒 01:49
3. In a bowl, combine 4 tbsp dried breadcrumbs, 150g firm tofu (not drained), and the microwaved onion. [Here's the key!] Use the tofu's moisture to soften the breadcrumbs and cool down the onion.
   🕒 02:17
4. Once the onion has completely cooled, add 150g ground pork, 1 egg, and 1/3 tsp salt to the bowl.
   🕒 03:05
5. Mix everything together by squeezing, then open your hands and mix evenly.
   🕒 03:16
6. Roughly divide the mixed dough into 4 portions.
   🕒 03:43
7. Lightly coat your hands with vegetable oil and take one portion of the dough at a time.
   🕒 03:54
8. Slap the dough back and forth between your hands to remove air bubbles, then shape it into hamburg patties. [Here's the key!] The tofu and breadcrumbs will make it fluffy, so don't worry too much about perfect shaping.
   🕒 04:05
9. Heat vegetable oil in a frying pan and place the 4 shaped hamburg patties.
   🕒 04:24
10. Sear the hamburg patties on one side over medium-high heat until golden brown.
    🕒 04:50
11. Flip the hamburg patties, add 2 tbsp water, cover with a lid, and steam-fry over low heat. [Here's the key!] Using a spatula to help flip them will prevent them from breaking. Steaming makes them plump and tender.
    🕒 06:07
12. In a separate bowl, combine 2 tbsp soy sauce, 2 tbsp Mirin (Sweet Rice Wine), 2 tbsp Cooking Sake (Rice Wine), 1 tbsp vinegar, 1 tbsp sugar, and 1/2 tsp potato starch. Mix well until everything is dissolved to make the sauce. [Here's the key!] Adding vinegar makes it refreshing, and pre-mixing the potato starch saves you the step of making a slurry.
    🕒 06:49
13. Remove the steamed hamburg patties to a plate.
    🕒 07:47
14. Wipe away any browned bits remaining in the frying pan from cooking the hamburg patties.
    🕒 07:58
15. Pour the prepared sauce into the frying pan and heat, stirring until it thickens.
    🕒 08:03
16. Pour the sauce over the hamburg patties on the plate.
    🕒 08:21
17. Serve 100g of squeezed grated daikon radish alongside the hamburg patties.
    🕒 08:33
18. Garnish with 4-5 thinly sliced shiso leaves.
    🕒 08:56