1. In large pot, bring 3 quarts of water to boil.
2. While water is heating up, in another large pot, saute onion, garlic, bacon and sage in canola oil.
3. When first pot of water is boiling, add potatoes, bring back to boil and continue cooking until potatoes are tender, about 10-15 minutes. Drain and set aside.
4. While potatoes are cooking, in a large saucepan begin heating milk, being careful not to boil.
5. In a frying pan, melt butter and slowly add flour, mixing with a wire whip, about 5 minutes. Add butter/flour mixture to milk, stirring well as sauce thickens, about 8-10 minutes. Add sauce to pot with sauteed ingredients and mix well with wire whip.
6. After potatoes are done, drain and transfer mixture to food processor and puree, forming a smooth paste. Transfer potato puree to soup pot and mix well, heating soup to serving temperature. Add milk if a thinner consistency is desired.
7. Serve in soup bowls garnished with a sprig of sage.
Makes approx. 1 gallon, or 15 - 8 oz. servings.