Heat a large skillet to medium high heat. Once hot, coat with olive oil and add garlic, onion, and jalapeño peppers. Saute for 3-5 minutes.

Add tenderloin and sear on all sides, 2-3 minutes time total. Place tenderloin and veggies into the slow cooker.

In a small bowl mix together maple syrup, coconut aminos (or soy sauce if using), mustard, and vinegar. Pour sauce on top of the tenderloin.

Set your slow cooker to low. Cook for 4-6 hours or until fork tender and cooked through. If using two smaller tenderloins it may cook only 4 hours, if you have one large tenderloin it cook take up to 6 hours.

Place arrowroot starch in a bowl and mix with 2 tbsp water. Pour inside the slow cooker and let thicken for the last 10 minutes of cooking.

Slice or shred the tenderloin and serve immediately with sauce.