Well first off understand that stealing off the counter is self rewarding. By doing it she gets food. So NOTHING gets left on the counters if you aren't RIGHT THERE. I don't care if you just went away for a minute. It can't get left on the counter. Period.
If nessecary buy some extra tall baby gates (or Xpen pieces) and block off the kitchen when you're preparing food.
Consider not letting her into the kitchen at all. This was actually highly effective for us with Apollo, he HATED being blocked out of the kitchen, so it didn't take many repetitions before he realized that stealing off the counter got him blocked out.
If she continues to try to get onto the counters consider scat mats (for example:
here, or
here or
here), or tinfoil (some dogs will play with tin foil, so becarefull if you use this, you don't want her eating that), or empty soda cans lined up on the edge where she knocks them down on herself.
As a last resort some of the higher end ecollar systems are adjustable enough to be used to keep animals off the counters. The good ones aren't cheap though. Petsafe makes one, but I've tried it and its not worth the money (it works, but it stops working in fairly short order and you end up replacing it). Dogwatch makes a couple different indoor systems, which last forever and work well, but they're not cheap.