This is a delightful twist to a popular soup dish that is delicious, quick, easy, and inexpensive to make. The red and sweet bulb onions offer a flavor and presentation that add a new dimension to classic French Onion Soup which I think you will enjoy.
Although onions and onion soups were enjoyed by the ancient Greeks and Romans, the oldest reference I could find for French Onion Soup is from 1651: “Potage of onion. Cut your onions into very thin slices, fry them with butter, and after they are fried put them into a pot with water or with pease broth. After they are well sod, put in it a crust of bread and let it boile a very little; you may put some capers in it. Dry your bread then stove it; take up, and serve with one drop of vinegar.” —The French Cook, Francois Pierre La Varenne,  Englished by I.D.G. 1653, Introduced by Philip and Mary Hyman [Southover Press:East Sussex] 2001 (p. 130)
The word “soup” comes from the word “sop.” Sop, because previous generations did not have the availability of utensils we have today, so bread was the means used to eat the soup by “sopping” it in the liquid.
French Red Onion Soup
1 Red onion, medium
1 Sweet bulb onion
4 T Butter
4 c Beef broth
1 T Balsamic vinegar
1 T Worcestershire sauce
½ t Tarragon, dried
¾ t Pepper, ground
Salt to taste
1 loaf French bread
Gruyere or Swiss cheese, freshly grated
Chop onions and sauté in butter until soft and caramelized (browned). Do not add salt until after this point else you will end up with wilted onions.
Add broth, vinegar, Worcestershire Sauce, dried tarragon, and pepper. Bring to a boil then simmer for 15 – 20 minutes.
Slice bread lengthwise and then into pieces that will fit in your soup bowls and place on baking pan.
Mince garlic and blend with olive oil. Brush olive oil and garlic blend on each bread face then sprinkle with dried parsley. Broil until bread begins to brown.
Grate cheese and sprinkle over bread slices. Then return pan to oven under the broiler until the cheese melts.
Place a slice of bread in each bowl and ladle soup over it.