Brush the surface of your griddle with 1 tbsp. of olive oil and heat the griddle to 350°F (176°C). Roast the onions, tomatoes and chile serrano on a heated griddle until the skin blisters and blackens in patches. You will need to turn the chiles and tomatoes to roast on all sides, but the onion can remain face down on the griddle, roasting without turning. Remove the vegetables when well blackened (see pic). Remove the stems on the tomatoes and chiles

Add all the vegetables to the container of a blender or food chopper, and pulse until ground and chunky. DO NOT over blend, as salsa should have texture.

Heat the 2 tbsp. (30 ml) of olive oil in a small skillet. Pour in the salsa, and allow the salsa to simmer over low heat for 10-15 minutes, until the salsa is reduced with little water remaining.