Remove the stems from the chiles, then cut or break them open and remove most of the seeds (you can scrape them out with a knife or just roll them in your hands and let them fall out). Cut the chiles into roughly ¼-inch pieces.In a large saucepan, combine the almonds, pepitas, sesame seeds, garlic and oil. Set over medium-high heat and cook until garlic and sesame seeds are highly golden but not browned, about 5 minutes. Remove from the pan from the heat and add the chiles. Let cool/steep for 5-10 minutes.Add the vinegar and sea salt to the pan along with the Mexican oregano. When the mixture has cooled to room temperature, pour it into a blender or food processor and pulse until everything is chopped into very fine pieces. Pulse a few times or run a short time, you aren't necessarily looking for it to be perfectly pureed and smooth, but more of a rough paste. Pour into a tight sealing glass jar and use right away or store in the refrigerator. It will keep for up to a month.