Why can I not make green salsa verde? I tried 3 recipes.

Today was my third try with the green salsa to eat with chips. Today I boiled the tomatillos then simmered them for ten minutes.
I put them in a blender with fresh cilantro , 2 garlic cloves, ¼ cup of chopped onion and half a jalapeno and it had a sour taste. Same with yesterday’s try. All I can come up with is I don’t roast the tomatillos and maybe they roast them on a grill in restaurants? Is that my problem? I even added sugar and it made no difference.