Step 1

In a medium saucepan, heat the oil over medium heat until hot. Add the onion and garlic and cover. Cook for 5-6 minutes, stirring once or twice to make sure the garlic and onions aren't sticking (adjust the heat if they are). Cook until the onions are soft but not browned.

Step 2

Stir in the flour and cook for 2-3 minutes, stirring constantly. It's ok if the flour clumps around the onions, just keep stirring to let the flour get golden and toasty.

Step 3

Gradually add the broth, whisking quickly and constantly to smooth out any lumps.

Step 4

Add all the remaining ingredients and bring to a boil. Reduce the heat to low and simmer for 30 minutes, stirring occasionally. The sauce should be silky and thickened - able to coat a spoon but still drip off. Add more broth to thin out if needed.

Step 5

Add additional salt to taste, if needed. The sauce can be processed in a blender if you prefer a smoother consistency. It will keep well in the fridge for up to 2 weeks. Otherwise, it can be frozen - probably up to a month or two if well sealed.