chipotle chili in a can
By now, many white-bread stores carry "Chipotles en adobo" which are whole chilies in tomato-y sauce. Look in supermarkets with large "ethnic food" sections, or in Mexican stores (in Mexican neighborhoods). The only puree I've ever seen was full of gunk and chemicals. If you buy "Chitoples en adobo" (La Morena is one brand), you can take out what you need to puree, and keep the rest. As long as you transfer the contents to a well-covered container once you open the can, and keep it refrigerated, it will last a long time.