Reduced to it's absolute essentials tinga is a tomato salsa spiced with chipotle. It's commonly used with chicken but goes well with pork also. The meat is shredded and added to the sauce and is very nice served in tacos or on a toastada.
Variations on the dish center on whether chorizo is added or not and also around whether the sauce is seasoned with something acid or with something sweet. I prefer the slightly sweet version, and although chorizo makes everything better I usually don't bother with it.
3/4 roma tomatoes (or 1 can of tomatoes).
1 clove of garlic.
1/2 of a tennis ball sized onion chopped, not too finely.
1 or 2 (according to your tolerance!) chipotles in adobo with some of the adobo.
Salt to taste.
A good inch of ground black pepper.
A pinch of oregano.
1 tsp (or more) of sugar.
The fussy method is to fry the onion till translucent, then add the chorizo and the garlic. Next add the roasted and peeled tomatoes and seasonings and cook everything together for 20 to 30 minutes, finally adding the shredded meat and the sugar and simmering everything together for a few minutes before serving.
A quicker method is to put the tomato, garlic, chipotle and seasonings in a blender, if a small amount of water is necessary to get the blades spinning ad that, and blend everything. Fry the onion for a few minutes then add the tomato mixture and cook together for 15 to 20 minutes. Finally add the meat and sugar annd simmer for another few minutes.
This recipe can be adapted very easily for the slow cooker.
I think the two important things to get right for this dish are not to shred the meat too finely and secondly to get the consistency of the sauce right. The sauce should be think enough to coat the chicken and the pieces of chicken shouldn't be broken down too much.