Combine oil, onion, salt, pepper, tomatoes, cayenne, sugar, paprika and garlic powder in heavy pot and simmer 25 to 30 minutes over medium heat. Mix flour and water in small bowl; add to onion mixture gradually, stirring until smooth and thick. Add cheese, stirring constantly to prevent sticking. Cook until well-blended and smooth. Serve warm with tortilla chips. Note: Some readers omit the oil because they think the cheese has enough fat. If so, saute the onion in 2 tablespoons hot oil to soften. This longtime Houston favorite from Felix Mexican Restaurant has been reprinted many times in the Chronicle. A similar recipe attributed to Felixs appears in the Houston Junior Forum cookbook, Buffet on the Bayou ($17.95), but the sugar is omitted and paprika increased to 3 tablespoons. Houston Chronicle, May, 1997. LPs note: This is most everyones favorite chili con queso. My friend Cyn says its the flour. Most recipes dont call for it. Hers is a bit different from this - more like the Buffet on the Bayou version. She claims to have gotten it from Felixs in Beaumont. According to her, it freezes well. By Lou Parris on May 13, 1997 Recipe by: Houston Chronicle, May 1997 Posted to MC-Recipe Digest V1 #620 by Lou Parris on May 26, 1997