How to discourage counter-surfing

Baby gates to block access when you can't be right on top of her to supervise would help. Also, training her to stay on a mat while you are doing food prep can help.

Some dogs are just hard-core though, and can't be trusted no matter what.

Your first step really needs to be management. Put up baby gates, or otherwise block access to the kitchen/table area. Every time she self-rewards by snagging something yummy to eat or fun to chew up, the habit will be all the more ingrained. Prevent her from rehearsing what you don't want to continue.

Second, work on training her to settle in a special place (dog bed, mat, etc...) whenever you are actively working in the kitchen or eating. Reward her VERY heavily for laying in her place with high-value treats. Teach her that being there is how she will get something wonderful, no need to go help herself.

Third - I'm not sure how much daily enrichment you are providing for her, but Aussies require a lot of mind games. Make sure her needs are being met in this area via puzzle toys, interactive feeders for meal times, nosework games & activities, etc... as well as appropriate physical activity.

Yes, management is key. Keep fun things off the counter. Block access to the kitchen. Reward heavily for keeping all four on the floor (or staying in her place) when food is about. The more she is allowed to practice the bad behavior, the more ingrained it will become.

I know management is annoying right now, but as she learns you can begin to loosen those restrictions. I had to keep everything off of tables and counters and away in drawers or cabinets when by Aussie/Collie was a youngster, and now he leaves any food on counters alone because he was never rewarded for it. He was, however, often rewarded for staying out of the kitchen and not jumping up on surfaces.