De or het champignonmengsel?

The correct Dutch article is:

het champignonmengsel

Rule Words ending in -sel: usually het. See the rule

How to use champignonmengsel

the champignonmengselhet champignonmengsel
this champignonmengseldit champignonmengsel
that champignonmengseldat champignonmengsel
our champignonmengselons champignonmengsel
your champignonmengseljouw champignonmengsel
every champignonmengselelk champignonmengsel
which champignonmengsel?welk champignonmengsel?
a big champignonmengsel / the big champignonmengseleen groot champignonmengsel, het grote champignonmengsel