I have also HSA Bank and am given the option between TD Ameritrade and Devenir.
As terran has said, TD Ameritrade offers SPTM which is a low fee (ER of 0.03%) ETF that tracks the entire U.S. market.
Just make sure that you enroll in commission free ETF's (through TD?) before buying.
My employer covers the fees associated with HSA Bank (and also contributes to it) but I ran the numbers and you would be better off paying the fees (If I remember correctly it was something like $5-6/mo) and investing as much as you can.
Off the top of my head, I think that you can invest anything over $1,000.