Heat avocado oil in a skillet over medium heat.
Stir in gluten-free flour blend as well as the chili powder into the oil.
Whisk till smooth.
It should be at a simmer, stir it often over medium heat for about 3 minutes.
(Each stove is different, so if your medium heat is too hot and it's sputtering a lot, turn down the heat some.)
Remove saucepan from heat for the next step.
Carefully add in the tomato sauce. (Tomato sauce tends to splatter when hot. Which is why you remove the pan from the heat.)
Add in the rest of the seasonings and brown sugar.
Add in the water.
Stir/ whisk till smooth.
Return to the stovetop and cook over medium-low heat.
Simmer with lid on, stiring occasionally for 5-10 minutes.
Serve/ use immedietly in your favorite Mexican recipes. Or cool down to room temperature before storing for later use.