Step 1 Boil the potatoes in salted water until tender, 15 to 20 minutes. When cool, peel then slice them.
Step 2 Cook the bacon over medium-high heat until crisp, 5 minutes. Remove it from the pan and set aside. Drain off any excess bacon fat, reserving 2 tablespoons. Add the flour to the fat in the pan and stir to combine. Do not brown. Combine the buttermilk and beaten eggs. Add to the flour mixture and cook, stirring, over medium heat until the mixture is thick and resembles melted ice cream, for about 5 minutes. Cool.
Step 3Wash the lettuce and tear it into pieces. Add the lettuce to a large bowl with the radishes, green onions and potatoes. Pour the buttermilk dressing over the vegetables. Add the bacon and season with salt and pepper to taste. Mix well and serve in large salad bowls.