I love homemade stock, and although I generally make poultry stock, I think the flavor comes mostly from the added veggies.
I put a bit of olive oil in the bottom of my soup pot, and saute some chopped onion, until it's carmelized, then I add the other veggies, usually chopped carrots, celery and parsnip until they start to soften a bit, then I pour my water over top of everything and toss in the greens from the celery, a whole onion including the skin, and a whole clove (or a couple of cloves, just not the whole head) of garlic including the skin. The skin on the onions adds a rich color to the stock. You can then season it a little bit if you wish with a bay leaf, some thyme and fresh parsley towards the end of cooking. I never add salt during the stock making process, but when you go to use it in recipes, you can add a bit to the final product.
I just put it on the stove and let it simmer for a few hours.
Once it's cooled a bit, you can drain it through a sieve and discard the veggies. Or, if you're like me, you can eat the completely soggy carrots.
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