Melt the butter in a large hot frying pan over medium-high heat.
Drain and cut the sweet potatoes into cubes. Add the sweet potatoes to the pan and sprinkle with the salt.
Fry the potatoes about 1-2 minutes.
Sprinkle in the brown sugar and cinnamon across the top. Wait 1-2 minutes and then toss the potatoes until the brown sugar has nice caramelization, about 1 more minute.
Remove from pan and serve immediately. Garnish with glazed walnuts if desired.
Notes
Store leftovers in an airtight container in the fridge for up to 4-5 days.