Add all marinade ingredients directly to a medium skillet and stir to combine.
Add the tempeh and toss to coat in the marinade. Arrange tempeh in an even layer in the pan and allow to marinate for about 5 minutes. Flip the slices and marinate for 5 more minutes.
Place the skillet on the stove over medium heat.
When the sauce begins to bubble, start stirring. The sauce will gradually thicken; keep stirring and occasionally flipping the slices to coat them with the sauce.
Once the sauce has thickened to the point where it's mostly coating the tempeh, it should begin to caramelize and become a nice golden brown. Give the tempeh a flip to brown both sides. You may want to reduce heat to low or medium-low near the end, as the sauce can go from nicely browned to burnt quite quickly.
When the tempeh is browned on both sides, remove it from heat and enjoy.