Bring lentils and 4 cups of salted water to a boil in a heavy 2-quart saucepan over medium-high heat. Reduce heat to low; simmer 20-25 minutes or just until tender.
Cook potatoes in boiling salted water to cover, 15 minutes or just until tender.
Drain the lentils and potatoes.
Cook bacon in a large skillet over medium heat until crisp.
Remove bacon and drain on paper towels, reserving 2 tablespoons of drippings in skillet.