Yes, you can substitute green tomatoes(Roma and others)when you make "Salsa Verde" The only difference you may encounter is that the tomatillos are more tart and/or astringent that regular green tomatoes, other than that they will work. You might also try asking your grocer to see if he can order them - Canned - They are available, probably through Old El Paso, Ortega, Rosarita, etc. It won't hurt to ask.

jimS/So Calif