To corn a beef brisket safely at home?

I avoid preservatives, nitrates, colorings therefore don't buy them. My mother inlaw made a excellent from scratch one - with salt and spices. It was dry- from the cut she chose, but so good and no preservation except the salt. I want to do this, but I am concerned with spoiling meat and making my children sick from it. The fact she pressure cooked it after would remove that chance of botulism right? is there any other way to prevent illness and do myself by curing and cooking or must it be pressure cooked. She froze some, I am reluctant to try that. Wouldn't bacteria have grown? I'd love ideas and recipes to do this safely but not with nitrates/nitrites. Is it possible?