4 medium tomatillos, husked, rinsed and cut in half (about 8 oz.)
3 cloves garlic, peeled
1 chipotle in adobo (more if you want more heat)
2 tbsp. cilantro (or more to taste)
Spray a large nonstick skillet with cooking spray and set over medium high heat. Lay in the tomatillos (cut side down) and the garlic. When the tomatillos are well browned, about 4 minutes, flip everything over and brown on the other side. The tomatillos should be completely soft.
Scoop the tomatillos and garlic into a food processor and add the chipotles, about 1/4 cup water, cilantro, and salt. Process everything together into a course puree. Taste and add 1/4 cup water and sour cream if necessary to lighten up the spiciness.