preheat oven to 425°F. peel and cube the sweet potatoes and yukon gold potatoes. wash redskin potatoes (do not peel unless u want to) and cube those as well.
place potatoes in a large saucepan. and enough water to cover potatoes. bring to a boil and cook for 3 minutes. drain thoroughly.
meanwhile place leeks into another saucepan and boil for 7-10 minutes or until just tender. drain and chop leeks.
use the 2 tbl. of oil and spread onto a baking sheet. toss together leeks and potatoes. spread out potato mix onto said greased baking sheet.
drizzle potatoes with remaining oil and sprinkle with tarragon,salt and pepper.
place potatoes in the oven and cook until browned and crisp. about 25 minutes.
( this goes great with a roast chicken or roast pork.)