Budapest: Onyx and Costes closed ,what to do?

[PalaceonWheels]

Hi all -

Leaving next week for 4 nights in Budapest, including 8/20 (St. Stephen's Day). I was working on last minute reservations and found out that Costes and Onyx are both closed for August holiday. We are looking for a higher end option - we prefer modern & creative but ultimately it is all about the food.

Reservation requests that are still pending:
Borsso
Fuchsli
Fulemule
Cafe Bouchon

Any other suggestions for a must do restaurant during our trip? We have a hotel room that overlooks the Danube for the fireworks on St. Stephen's Day - any suggestions for a meal that evening?

sks..