Mix ground beef, breadcrumbs, caramelized onion, egg, Worcestershire sauce, herbs, salt, and pepper.

Shape into patties and sear both sides in a pan until browned.

Combine soy sauce, ketchup, and Worcestershire sauce in the pan; simmer patties in sauce.

Boil potatoes until soft, mash with butter, milk, and herbs.

Coat cut and ice bathed fries in cornstarch and flour, fry once at 160°C, cool, then fry again at 190°C until crispy and light golden color.

Toss fries with melted butter, garlic powder, and dried parsley.

Serve hambagu steak over mashed potatoes, pour sauce, and sprinkle with herbs. Add fries on the side.