IN A GLASS MEASURING CUP, COMBINE 1 CUP WARM WATER, YEAST , THE MILK
AND SUGAR. LET STAND UNTIL FOAMY, ABOUT 7 MIN. MEANWHILE, BEAT ONE EGG.
IN A LARGE BOWL, WHISK FLOURS WITH SALT. ADD BUTTER AND RUB INTO FLOUR
BETWEEN YOUR FINGERS, MAKING CRUMBS. STIR IN YEAST MIXTURE AND BEATEN
EGG UNTIL A DOUGH FORMS. SCRAPE DOUGH ONTO CLEAN, UNFLOURED COUNTER
AND KNEAD, SCOOPING DOUGH UP, SLAPPING IT ON COUNTER AND TURNING IT,
UNTIL SMOOTH AND ELASTIC, 10 MINUTES.
SHAPE DOUGH INTO A BALL AND RETURN IT TO BOWL. COVER BOWL WITH PLASTIC
WRAP AND LET RISE IN A WARM PLACE UNTIL DOUBLED IN BULK, 2 HOURS.
LINE A BAKING SHEET WITH PARCHMENT PAPER. DIVIDE DOUGH INTO 8 EQUAL
PARTS. GENTLY ROLL EACH INTO A BALL AND ARRANGE 3 INCHES APART ON
BAKING SHEET. COVER LOOSELY WITH A CLEAN KITCHEN TOWEL AND LET BUNS
RISE IN A WARM PLACE FOR 2 HOURS.
SET A LARGE SHALLOW PAN OF WATER ON OVEN FLOOR. PREHEAT OVEN TO 420
DEGREES WITH RACK IN CENTER. BEAT REMAINING EGG WITH 1 TABLESPOON
WATER AND BRUSH SOME ON TOP OF BUNS. BAKE, TURNING SHEET HALFWAY
THROUGH BAKING, UNTIL TOPS ARE GOLDEN BROWN, ABOUT 17 MINUTES.
TRANSFER TO A RACK TO COOL .