Chicken burger with kewpie mayonnaise

For burger buns
Combine flour, yeast, sugar, salt and egg in a mixer bowl. Start kneading on medium speed for 5 minutes, at the same time slowly dripping water into the bowl.
When the dough has formed a ball, add butter and continue mixing for 10 more minutes. The dough should be smooth and shiny, and slightly tacky but not sticky.
Form into a ball and let rest for 10 minutes, covered with clean kitchen towel or plastic.
At the end of the resting period, the dough will be 1,5 times bigger than before. Lightly press to release air bubble.
Divide dough into 10 portions for normal buns or 20 for mini buns.
Shape into balls and arrange on buttered pans. Leave to proof for 90 -120 minutes, till the dough is 3 times the original size.
Preheat oven to 190 degree celsius. Bake the buns for 15 minutes till nicely browned. When the buns are out from the oven, quickly brush the top with some butter.
Set aside to cool on wire rack.
For chicken patties
Combine all ingredients in a bowl. Mix well.
Shape the mixture into 10 patties, weighing about 150 g each.
Heat some oil in a non-stick pan. Cook the patties till golden brown, 5-8 minutes each side, over medium heat.
Remove from heat and arrange the patty between buns, layered with lettuce and spread some mayonnaise on top of the patties.