We have a number of tournaments scheduled at the Turf bar in Fargo.  Generally we see a turnout between 7-10 teams.  As large is a relative term, I'll let you decide how big our tournament is.  We bring in a second table to keep things moving and the first tournament lasts somewhere around 4 hours.  We run an additional tournament after that with whoever sticks around.  The remaining dates in Fargo are as follows.
Saturdays @1PM
FEB 19
MAR 12
APR  9
APR 30
$10 Entry Fee Per Player (Draw Partners)
There is a tournament in Grand Forks Feb 26.  Other than that I don't know of any Foosball tournaments happening in the immediate region.  If any of those dates work for you, we're always happy to have new players in the mix.