Thinly slice the onion.
Add the pork tenderloin to the base of the slow cooker. Season with salt and pepper. Add the thin onion slices on top. Pour the teriyaki sauce on top. Add the minced garlic and crushed red pepper flakes over the top.
Set on low and cook for 8 hours.
Just before dinner, cook the rice as directed.
Remove tenderloin from the slow cooker and let sit for 5 minutes before slicing or shredding. Spoon sauce out of slow cooker to serve over sliced or shredded pork pieces.
Prepare veggies.
Serve Teriyaki Pork Tenderloin with sliced green onions or sesame seed garnish, rice and veggies.
To Freeze: Place pork tenderloin, sliced onions, minced garlic, crushed red pepper flakes and teriyaki sauce into gallon size freezer bag or vacuum sealed bag. Freeze. Thaw and slow cook as directed.