The general cure for this is to add an egg and some breadcrumbs to your ground meat mixture. The eggs serve as a binding agent, and the breadcrumbs remove excess moisture.
If your recipe does not allow the use of these workarounds, there are still some things you can do to improve your result:
- Increase the density of your mince: there is quite a lot of difference in how large or small the chunks of meat in your mince are when you buy it. A real craftsman butcher will allow you to buy finer mince by changing the setting on his mincer. The finer the mince, the denser and tighter the meatballs will be.
- Work them! Many cooks tend to be a bit lazy when it comes to rolling meatballs, working on the "once it's round, it's done" principle. This means that they do not bother to roll them longer and harder to improve the structural integrity of the balls.
- Turn up the heat: Good hot oil/butter and plenty of it helps you to get a solid crust around the meatballs, which in turn lowers the chance of them falling apart.
- Bigger is NOT better. Smaller balls have less tendency to fall apart.
I hope this helps any in making the recipes more successful next time!