While oven is heating, place Roma tomatoes, garlic, onions and jalapeño on a baking tray. Season with 1/2 tsp kosher salt. Toss with canola oil and roast in the oven for 15-20 minutes. You should have a nice char on the vegetables. Toss the vegetables about halfway through cooking.
While the vegetables are roasting, remove the stem and seeds from the guajillo chilis. Place the chilis in a small pot and cover with water. Place the pot on the stove and bring to a boil; turn down the heat and simmer for 5 minutes, until the chilis are soft.
Strain the water from the chilis and place the chilis in a food processor. When the vegetables are done roasting add them to the food processor along with the lime juice, cilantro and 1 tsp kosher salt. Blend until smooth. Taste and adjust salt to your liking.
Serve alongside McClaren Farms Skirt Steak tacos.
It is important to remove the seeds from dried chilis. They are different from fresh chili seeds that make things spicier. Dried chili seeds will make things more bitter.