Melt 1 tablespoon butter with olive oil in large nonstick skillet over medium-high heat. Add Jerusalem artichokes and half of sage. Sprinkle with salt and pepper. Sauté until brown and just beginning to soften, turning frequently, about 10 minutes. Using slotted spoon, transfer Jerusalem artichokes to shallow serving bowl. Add remaining 2 tablespoons butter and sage to skillet; fry until sage darkens and begins to crisp, about 30 seconds. Add lemon juice; simmer 1 minute. Pour lemon-sage butter over Jerusalem artichokes in bowl, tossing to coat. Season with salt and pepper. Sprinkle with parsley.