Rec: Chipotles in Adobo sauce. This is untried, I copied it before they were readily available.
I think it came from one of my chile books, it is from Mark Miller of Coyote Cafe. One source for the dried chipotles is Penzeys. I love to use them whole in pinto beans, chile, etc.
Chipotles in Adobo sauce
10 chipotle chilis, stems removed and slit lengthwise
1/3 cup white onions, 1/2 inch slices
5 tablespoons cider vinegar
2 cloves garlic, sliced
4 tablespoons catsup
1/4 teaspoon salt
3 cups water
Combine all ingredients in nonreactive saucepan, cover and cook over very low heat for 1 to 1 1/2 hours until chiles are very soft and liquid has reduced to 1 cup.