In Sacrifice of Angels Kira and Leeta, Rom and Jake were being held by the Dominion.
Quark (and Tora Ziyal) came in bearing Hasperat Soufflé, hypo-sprayed the Cardassian jailer and killed the two Jem'Hadar guards before taking down the forcefield.
This seems to be the incident that she's referring to.
(Quark enters brandishing disrupters. The Jem'Hadar spread out.)
QUARK: All right, no one move!
ROM: Brother! I knew you would come.
QUARK: It's a surprise to me. Now, just keep calm and stay where you are. Understand? Don't move. You, open the holding cells. I said,
open the holding cells.
ZIYAL: You just told them not to move.
QUARK: Right. Nobody moves except you. Now open the cells.
(The Jem'Hadar look at each other then tense up. Quark kills them both
in total surprise.)
KIRA: Take down the forcefields.
(Ziyal takes a disrupter from Quark and blasts the control panel.)
KIRA: I'd kiss you, Quark, but there isn't time. We have to find a way to shut down the power to the main computer.