If using tomatoes: Fill a large stock pot with water and bring to a boil on the stove. Remove the stems and wash the tomatoes well. Using a slotted spoon, place the tomatoes one at a time in the boiling water and allow to blanch for 1 minute.

Remove the tomatoes from the water and allow to cool. The skin should split away from the tomato. Using a fork and knife, remove the peel from each tomato. Cut away the core and slice the tomatoes in half. Scoop out the seeds and place the prepared tomato in a large bowl.

If using tomatillos: Remove the husks and wash the tomatillos well. Place the tomatillos in a large stock pot and cover with water. Place on the stove and bring to a boil. Simmer over medium heat until the tomatillos have turned from bright green color to olive drab.

Using a slotted spoon, remove the cooked tomatillos from the boiling water and place in a large mixing bowl. Pour off any water that may accumulate in the bowl. Allow the pot of water to cool completely before discarding the cooking water.

To Prepare the Salsa:

Heat the broiler of your oven. Place the peeled garlic and chile serrano on a baking sheet lined with parchment paper. Drizzle a few teaspoons of olive oil over the garlic and chiles. Roast the garlic and chiles under the broiler for 2-3 minutes until the chiles are blistered and the garlic has light golden-brown spots. Remove the baking pan from the oven and allow the chiles and garlic to cool.

Add the roasted chiles and garlic to the bowl of tomatoes or tomatillos. Add salt to taste. Puree well with an immersion blender.

In a large skillet on the stove, add 2-3 tbsp. (about 45 ml) of olive oil. Heat gently over medium flame and then add the tomato or tomatillo puree. Stir and allow the salsa to simmer until it is reduced. Tomato salsa can take from 30-45 minutes to reduce depending on the juiciness of the tomatoes. Tomatillo salsa will take approximately 10 minutes to reduce completely.