Yes. French is a noun, so you capitalize it. I'm not sure about fries, though, but it is an object, so technically the correct way to write it is French Fries.
Grammatically, only French should be capitalized.
Exceptions can be applied for writing menus etc, however, to comply with a design/style.
oui
"Cream of onion" definitely has cream in. Whereas "onion soup" may not; it's more likely to be French Onion style soup.
french onion soup
There are some great recipes of French onion soup on www.foodnetwork.com. The website also gives ratings and reviews on French onion soup recipes. These recipes are easy to follow and provide accurate ingredients and cooking times needed to make a French onion soup.
French onion soup does not always come in a lion's head bowl. When it does, it's because of tradition. Lion's head bowls are designed in a classic French style. Many restaurants in the United States serve French onion soup in ramekins.
soupe à l'oignon
about 10 euros
Traditionally, it has melted gruyere cheese on top, which is French.
Any sort of soup is a mixture.
Julia child's recipe uses Merlot, with its lower tannins, in her French Onion Soup recipe. I've found none better.
The French Chef - 1962 Your Own French Onion Soup 1-3 was released on: USA: 1 January 1965
A Frenchman.
There are lots of websites which offer french onion soup recipes. A great place to look is on The Food Network they have several versions of french onion soup. Also All Recipes is another option, all of their recipes are rated by community members.