Some of your 'shortcuts' are not good ideas. Definitely start with cold water. Definitely bring up the temp slowly. Definitely do not boil. Do add aromatics upfront to the broth, but remove them as they get mushy so they don't cloud it.
Standard ratio for beef broth would be: 8 pounds of bones to 6 quarts of water to 1 pound of veggies (onion, leek, carrot) to one 'boquet garni', essentially garlic, rosemary, anise flavoring for pho, and bay leaf, plus whatever else I forgot.
If you have 'pond water', which I interpret as thin-tasting, you probably put too much water in the second time -- this is fixable by slowly evaporating out the water until it gets to a good texture. If you skimmed properly, it will be clear as you do this. I will typically strain through a kitchen towel or cheesecloth as the liquid evaporates down.
I'm guessing you put in like a gallon of water, so you had like three or four times too much water.
As a warning which you probably already know, you are not going to be able to duplicate your local pho joint's broth -- the broth recipe is the thing for pho makers, and they probably have a bunch of tricks they use, including using a neverending supply of yesterdays pho, that you won't be able to do at home. That said, you should be able to get a good beef broth if you follow some basic rules for making stock.
Best Answer
Chow mein is a Chinese dish of stir fried noodles. While popular throughout Chinese cuisine, I am guessing that you are referring to the dish found at Chinese restaurants throughout India, the UK, or the US. In these restaurants, a protein such as chicken, beef, or seafood is often added. Remember, these are high heat, fast-cooked dishes, most often cooked in a wok. So, the proteins must be cut small enough to cook quickly, and lean enough to result in a tasty and tender bite. There is not time to render fat or break down collagen when stir frying. So when considering beef, pork, or lamb specifically, cuts that lend themselves to quick cooking are chosen. For beef, I would say sirloin or flank are two good options. In the end, this ingredient choice is mostly about cooking method.