How can I keep tomatillos submerged in water during boiling? I like making enchiladas verdes, but I have an annoying time keeping tomatillos submerged when I boil them. The top part of them remain out of surface. 

I try to keep them held down with a long wooden spoon. But I can't just stand there holding them for 5 to 10 minutes.  

Any suggestions.
Use a metal wire strainer turned upside down in a larger cooking pot so that the tomatillos can bob around in the water but always be under the surface.  If for some reason the strainer doesn't stay down under the water, put some weight on the top.