If possible, avoid processed foods and that will take care of the sodium problem.
Now that it's summer time, there's bound to be a bounty of tasty, fresh fruits and vegetables available at a local farmer's market as well as fresh herbs that can add flavor. Good food naturally tastes good, no added sodium needed.
If that is not an option, shop in the natural foods (aka hippy food section
) area of the grocery stores. Most of those products will be low sodium and some will be marketed as such. Read the nutrition facts label to get the full scoop. Dried herbs like basil, oregano, cumin, anise, etc also add lots of flavor. If she likes spicy food then you'll have no problem, just toss dried chile flakes or fresh, diced hot peppers into her favorite dishes