Initially, collect and measure all the required ingredients.
The first step is to prepare the Guajillo chiles. In this step, you have to remove the stem and seeds and then toast the chilies for 30 seconds.
Second step is to rehydrate the chiles by immersing into hot water for 15 – 30 minutes.
Third step is to sauté the chopped onion and garlic in olive oil over medium heat.
Fourth step is to blend all the ingredients to make the sauce base.
Fifthly, adjust the consistency using the reserved water from rehydrating the chiles.
Sixth step is to simmer the sauce for 5 to10 minutes to get desired consistency and flavors.
Last step is to serve the sauce or store the sauce in air tight glass container into the refrigerator.