Shallots have a milder taste and odor than onions, so shallots are more commonly eaten raw. However, when cooked, shallots can lose their flavor quickly, and so onions are preferable in cooked food like stir fries. Onions are also crunchier than shallots.
Onions and shallots are both bulb vegetables in the same plant family that originated from central Asia. They are both used as ingredients to flavor dishes and can be eaten on their own.
edit What is a Shallot?
A shallot is technically a type of onion. Historically, shallots were their own species (Allium ascalonicum) but they are now classified as a variety of the Allium cepa (onions).
Shallots can be distinguished from the common onion by their appearance. Shallots are smaller and have longer, slimmer bulbs than the common onion. Both vegetables have a similar taste but shallots are less pungent.
100g of onions contain 9.34g of carbohydrates, 1.1g of protein and 0.1g of fat. They also contain 1.7g of dietary fiber and 23mg of calcium. 100g of shallots contain 16.8g of carbohydrates, 2.50g of protein, and 0.1g of fat. They are rich in vitamins and minerals.
edit Calories in Shallots vs. Onions
Shallots have more calories than onions. 100g of onions contain 40 calories while 100g of shallots contain 72 calories.
edit Health Benefits
Onions are rich in fiber and allicin, which reduces cholesterol and blood pressure. They are also a rich source of quercitin, which has anti-carcinogenic and anti-inflammatory functions.
Shallots are a rich source of anti-oxidants, such as quercetin, and kemferfol, and are also a good source of allicin. They are also rich in vitamin A, phridoxine, foliates, thiamin, and vitamin c, and contain lots of iron, calcium, copper, potassium and phosphorus.
edit For Diabetics
Both onions and shallots contain allicin, which helps lower blood sugar levels in diabetics. Onions are also a rich source of chromium, which helps tissue cells respond appropriately to insulin.
edit Substituting Onions for Shallots and Vice Versa
Depending upon the recipe, it may be possible to substitute onions for shallots and vice versa. The general rule of thumb is 3 shallots are equivalent to 1 onion, considering the differences in size and pungency. If a recipe calls for raw shallots, it's hard to substitute onion because the taste will be stronger.
edit Onion and Shallot Recipes
Onions are often chopped and used as an ingredient in many dishes, and can also appear as the main ingredient in dishes, such as French Onion Soup or onion chutney. Caramelized onions go well with mushrooms. Some shallot recipes include goulash, glazed baked onions, ratatouille and undercover onion tart at abelandcole.co.uk.
This YouTube playlist has a few recipes that use onions as one of the ingredients.
Shallots can be used in fresh cooking, as well as being pickled. Shallots recipes include caramelized shallots, and a wide range of recipes, including Roasted Butternut Squash and Shallots, Pork Chops in Balsamic Vinegar and Shallot Sauce and Roasted New Potatoes with Shallots, are available at Food.com.
This list of videos presents a few recipes that use shallots.