Pulse together maple syrup, oregano, chipotles, adobo, garlic, lime zest and juice, vinegar and cumin in a small food processor. Season with salt and pepper. Reserve 2 tbsp of mixture and set aside. Brush remaining mixture over the pork, place on plate, cover with plastic wrap and refrigerate for 2 to 6 hours.
Remove pork from fridge and bring to room temperature, about 30 min. Heat oven to 375F (190C).
Heat oil in an oven-proof or cast-iron skillet over medium-high heat. Add tenderloin and cook until brown on all sides, about 4 to 6 minutes.
Place pan in oven and continue to cook until desired doneness is reached (between 140-160F, 60-70C), around 12 to 18 minutes.
Remove pork from oven, transfer to a cutting surface, brush with remaining mixture and tent with tinfoil. Rest for 10 minutes before slicing very thinly for tacos.
Warm tortillas according to package directions and serve with pork.