Preheat oven to 450 F.
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.