For salmon patties I have used 1/2 cup of rice or quinoa as a binder. I blend it with the canned salmon in a food processor and season it as I like. When making taquitos I have used a little bit of mashed potatoes as a binder with the ground beef inside the tortilla. It worked out really well! Recently, I used mashed potatoes in a meatloaf recipe. It did a great job of making it stick together like an egg would. I took one potato and just mashed it up. Then I added it to 1.5 lbs of ground beef and the other meatloaf ingredients here.(below) I used GF rice crispies instead of bread crumbs, and the potato instead of an egg. It did change the texture some (be warned) but it did the job well. I also reduced the milk to 1/4 cup (rice milk). Thanks allrecipes.com for the recipe!