In a large saucepan, heat the oil over medium heat. Stir in the flour to form a paste and cook for 1 minute, stirring constantly.
Whisk in ½ cup of chicken stock immediately; it will quickly form a thick, smooth paste.
Add the remaining chicken stock, tomato sauce, salt, pepper, and 2 Tablespoons of the Spice Mix. Whisk to combine.
Increase the heat to medium-high and cook for 3 to 5 minutes, whisking frequently, until the sauce thickens. Remove from heat and set aside.