Heat oven to 400°F.
Line a baking sheet with lightly oiled aluminum foil, if desired, and heat the baking sheet in the oven for 4 - 5 minutes.
Scrub the potatoes, chop into bite-sized pieces and pat dry. Place in a large bowl.
Whisk the oil and lemon juice together, then drizzle over the potatoes and toss until very well-coated.
Spread out potatoes on baking sheet so they are not touching each other.
Bake for 15 to 20 minutes, turning once or twice until crispy on the outside and tender when pricked with a fork.
Meanwhile, lay lemon slices on a grill and cook until slightly caramelized and golden brown, about 5 minutes, flipping once. Use as a garnish for the potatoes.