Ahah... I don't put anything into my tea anymore. [a soft chuckle.] No one does that in Inazuma for their teas. But since this is Mondstadt tea...

I usually drink with just a bit of milk.

[but first! thoma adds milk to diluc's cup and offers it up to him, hand still around the little cup of milk that he'll be adding to his tea soon. he really didn't think diluc was going to pour him anything, he just thought the man was making conversation.]