Making a test tiny roast

I make a lot of home cured corned beef so the seasonings are pretty set. When I first started, I didn't try to make a soft tiny roast to test the seasoning, instead I sliced off a thicker slice and cooked in slowly on the stovetop until it was done to my liking then tasted it. I wasn't worried about making it soft and tender when I was testing for seasoning. One of the best ways to make a roast soft and tender is to use a sous-vide immersion circulator. Set it to your final temperature, let the water heat up, put the roast in a plastic bag, remove the air and cook until tender. You can find dozens of resources about sous-vide cooking on-line.

What is important with food safety when cooking meat is to get to a specific minimum safe temperature for the meat being cooked. Sometimes, you must not only reach that temperature, but the meat must also remain at (or above) that point for a period of time to ensure food safety; this is why some meats require a resting period. While the resting period can also have other benefits, those are out of scope for this question, and will not be addressed here.

The following chart gives a brief overview of the issue you are bringing up, although there are more in-depth details available online, if you should wish to look deeper into the matter.