Add flour and whisk until well combined, about 1 minute.
Add remaining ingredients except salt and pepper, whisk, bring to boil, then reduce to simmer.
Simmer for 10 minutes or so, until thickened, whisking occasionally.
Season with salt and pepper.
This can be stored for up to 1 week in the refrigerator in an airtight container. It also freezes well.
This recipe is not made with what America called Chili Powder which is a mix of spices, not just chili. Because American Chili Powder differs from brand to brand and is not available all over the world, this recipe is made from scratch, essentially making a DIY American Chili Powder.