Can a mortgagor collect the remains of a tax foreclosure & sale after the debt is satisfied?

Short answer? Yes, you can. But, it is not guaranteed that even if there is a surplus you will be able to collect any. As the debtor, your rights to surplus proceeds come last to just about everyone else with a claim. However, assuming there is anything left over beyond what is owed to the clerk for costs and the mortgage holders for their debt, then you can apply for the surplus. Should you elect to do that, I would recommend consulting a local attorney to help you navigate the matter because there are procedural hurdles on these types of things which can trip up the uninitiated.

The short answer is "yes," though you may have to navigate through state and municipal legal hurdles in order to do so. Consult with a real estate attorney to determine your best options moving forward. Good luck with your case!