•Peel and cut rutabaga into 2-inch chunks.
• Place in 4-quart saucepot cover with water; season well with salt and simmer for about 20 minutes or until it's very tender. Drain well in colander.
• In same saucepot, boil cream and reduce by half; add sage leaves as the pot comes off the heat. Place drained and cooked rutabaga in blender (in batches if needed), add cream and blend well until very smooth. Add butter and blend again checking for seasoning. Reserve warm.
• In a clean 4-quart saucepot, heat oil to approximately 350 degrees (a water droplet should boil, hiss, and evaporate quickly).
• Lightly flour then fry onion slices in batches until just golden brown and crisp. Allow to drain and cool on paper towels.
• Serve hot puree with crisp onions.