Put the chicken fillets, garlic clove, the bay leaf and the salt in a pot and cover everything with water. You will need the liquid in which the chicken was cooked, so make sure to be generous with the water.Turn the heat on and bring them to the boil before lowering the heat down and let them simmer covered until the chicken is fully cooked (about 20 minutes).
When the chicken is cooked, take it out of the pot and reserve the cooking liquid. Shred the chicken using 2 forks and leave it to the side while you get on making the mole.
Put the mole paste in the blender or food processor. Add the chocolate, stale bread (if using a roll, break it into pieces so you don't clog the blender), tomato puree, the chicken stock powder, the peanuts, the onion and 1.5 cups of the reserved liquid where the chicken cooked. Blend everything together to form a runny sauce.
Melt the lard at low heat in a non-stick pan deep enough to hold all the sauce. Pour the mole sauce and use another 1/2 cup of the liquid where the chicken cooked to rinse the blender and any leftover content into the pan. Stir constantly to avoid the sauce sticking to the pan or thickening too quickly. If this happens, don't worry, add a bit more of the reserved liquid from the chicken (a 1/2 cup at a time) and mix well to thin the sauce. I normally use another full cup of liquid so 3 in total. The thickness of the sauce is a matter of taste. I like to be able to covered my mole tacos in this rich sauce without having them swimming on it and going all soggy. So my mole sauce is thick as suppose to runny. I urge you to try it both ways and see which one you like most. It's just a matter of taste and texture. When you are happy with the thickness of the sauce. Remove it from the heat.
Get a non-stick pan on the hob and turn on the heat to a medium high. Heat your tortillas in the pan (about 40 seconds on each side) one at a time and wrap them in a thick tea towel until all eight are heated. You are now ready to assemble your chicken mole tacos. Have two warm plates ready as it is best to prepare them on the plate you're serving them.
Take a warm tortilla, stuff it with plenty of shredded chicken and fold it in half (resembling a quesadilla). Place it on the warm plate and repeat this step until you have 4 warm tacos on each plate. I kind of over lap them a bit.
Pour the still hot mole sauce over the chicken tacos making sure they're well covered. Sprinkle the toasted sesame seeds over them and slices of fresh raw onion. Finish off with a generous drizzle of sour cream.
We loved this dinner the mole chicken tacos were very satisfying and to top it all up and the dessert recipe came out courtesy of Nigella Lawson's Christmas Book, it's a delicious, light and fluffy pudding and the hot chocolate sauce is devine!