Share 'Any tips on making a vegetable bed in a lawn?'

I have a typical Ontario garden - large area of lawn with a couple of trees and clumps of perennial flowers around the edges. I have been gradually adding vegetable plots over the last few years but digging up the turf is hard work. I'd like to make a decent sized plot to grow potatoes which rather exclude the use of landscape fabric. I did hear of somebody covering parts of the lawn after the sn…