Preheat oven to 400°–425°F (temperature will depend on type of oven). Lightly toss the tomatoes, onions and jalapeno peppers in oil, then place on a sheet pan. Cool completely.
While the vegetables are roasting, toast the arbol peppers. Toast the peppers in a hot, dry skillet until the skins blister and the toasted aroma fills the air. Cool. Place in a small saucepan and cover with water. Bring to a boil. Remove from heat and cool for 15 minutes. Drain (reserve the liquid).
Combine the roasted vegetables, drained arbol peppers and the remaining ingredients into a blender. Blend to small chunky smooth.
Cool completely. Store in a container with a lid. Label, date and refrigerate.