Preheat oven to 375°F.
Peel potatoes and carrots, cut them into very small cubes. Dice the onion and celery into small pieces. Mix all the veggies together put in a microwave safe bowl, cover and cook in the microwave about 6 minutes, until the potatoes and carrots are slightly tender. In the mean time brown the meat.
Mix the cooked meat into the veggies and spoon into the prepared pie crust.
Mix the bouillon and hot water together making sure it's completely dissolved. Pour over the meat/veggie mix. Pour in the cornstarch mix for thickening. Add salt and pepper to taste, (but I take it easy with the salt because of the bouillon). Cover with the top crust and bake for about 1 hour, until the crust is nicely brown.
I use a home made pie crust (the Crisco recipe). I find it works better than a frozen crust. It is a little hard to serve, the filling falls out frequently, but it never seems to last long enough on the plate for anyone to worry about.
My diabetic father eats this with great pleasure and no risk, everything is very lean, I drain the meat after cooking if my dad is having some, and there is obvious fat. My mom has high blood pressure, and eats this with no problem as long as I limit the salt or don't add any at all (the bouillon is salty enough).