Cut potatoes into bite-sized pieces, rinse, and drain. Place in a microwave-safe dish, sprinkle with 1/4 tsp salt, cover loosely with plastic wrap, and microwave at 600W for 4 minutes.

Slice the onion thinly and cut bacon into strips.

In a saucepan, melt butter over medium heat, add flour, and mix well. Gradually add milk in portions, stirring continuously until smooth.

Heat salad oil in a frying pan over medium heat, sauté onion and bacon until softened. Add salt, potatoes, and white sauce, mixing well.