Preheat oven to 400. Toss the sweet potato with some salt and olive oil on a sheet pan. Roast until fork tender, about 20-30 minutes.
Cook the sausage in a frying pan until browned, breaking it up into small crumbles as it cooks.
Add the sausage to a bowl with the sweet potato and mash until smooth. Stir in the scallions and the soy sauce.
Open the spring roll wrappers and cover with a damp paper towel to prevent them from drying out.
One by one, add some filling and roll the spring rolls. Make them thin and long as opposed to short and fat. Use a little water to seal them, and keep them seam side down until ready to fry.
Preheat the oil to 350 and fry for a minute or two until starting to brown
For the sauce - mix all the ingredients together in a bowl. Adjust seasoning to personal taste.
Serve the spring rolls with the sauce.