Beth's Mexican Frittata

Preheat oven to 350 degrees. If necessary, take sausage out of casing and cook in a separate pan, breaking it up, until no longer pink. Drain, if needed. Slice potatoes very thinly (can use a mandeline slicer.) Heat oil in an ovenproof skillet. Place potatoes in a single layer in pan and cook potatoes until golden brown. Beat together eggs, milk, flour and salsa with a whisk. Add sausage to cooked potatoes. Add egg and milk mixture to pan; heat until almost firm. When egg mixture is almost firm, add cheese and bake until eggs are firm and cheese melts.