This depends on the thickness of your slices. (saffrontrail.com)
Just wanted to ask what is the thickness of the slices that you make? (tasteloveandnourish.com)
Cover and reduce to a simmer for 30 minutes, then uncover and continue to simmer another 10 - 15 minutes, until tender (depending on the thickness of your slices). (thepaleomom.com)