Cheese & Onion Fondue

1 oz Butter
1 lg Onion -- finely chopped
2 ts Plain flour
5 Fluid ounces thick sour cream
8 oz Gruyere cheese -- grated
8 oz Cheddar cheese -- grated
1 tb Chives -- chopped
Pepper
sm Cooked potatoes -- to serve
sm Cooked sausages -- to serve

Melt butter in saucepan, cook onion for 4-5 minutes
until soft. Stir in flour, then add cream, cook for 2
minutes. Continue to cook whilst adding cheeses and
heat until mixture is smooth, stirring frequently. Add
chives and season with pepper. Pour into fondue pot
and serve with the potatoes and sausages.