I hate to be a pest, but:
Brown all the meat under the broiler and set aside.
What temperature and for how long?
The carrots and baking soda sound like a great idea. The acid in the store-bought sauce bothers me too.
The broiler in my oven doesn't have a temp setting,it's just broil. I don't have a time because the closer you put the oven rack the faster it browns. I don't put it on the highest spot but rather two down from the top so it doesn't brown too fast. Time is subject to you oven.
But you just keep an eye on it so it just gets some color you don't want it dark brown you're just trying to get a light brown color cause it cooks in the sauce.
If the acid bothers you, you will like this much better. If you watch the texture of the sauce it actually changes when you add the baking soda. As a matter of fact after you take it out of the freezer you will add a little water to it to thin it out as it thickens up even more in the freezer.