Char: Turn your broiler on high and move rack to the highest spot. Place ginger and onions on baking sheet. Brush just a bit of cooking oil on the cut side of each. Broil on high until ginger and onions begin to char. Turn over and continue to char. This should take a total of 10-15 minutes.
Parboil the bones: Fill large pot (12-qt capacity) with cool water. Boil water, and then add the bones, keeping the heat on high. Boil vigorously for 10 minutes. Drain, rinse the bones and rinse out the pot. Refill pot with bones and 6 qts of cool water. Bring to boil over high heat and lower to simmer. Using a ladle or a fine mesh strainer, remove any scum that rises to the top.
Boil broth: Add ginger, onion, spice packet, beef, sugar, fish sauce, salt and simmer uncovered for 1 1/2 hours. Remove the beef meat and set aside (you’ll be eating this meat later in the bowls) Continue simmering for another 1 1/2 hours. Strain broth and return the broth to the pot. Taste broth and adjust seasoning – this is a crucial step. If the broth’s flavor doesn’t quite shine yet, add 2 teaspoons more of fish sauce, large pinch of salt and a small nugget of rock sugar (or 1 teaspoon of regular sugar). Keep doing this until the broth tastes perfect.
Prepare noodles & meat: Slice your flank/london broil/sirloin as thin as possible – try freezing for 15 minutes prior to slicing to make it easier. Remember the cooked beef meat that was part of your broth? Cut or shred the meat and set aside. Arrange all other ingredients on a platter for the table. Your guests will “assemble” their own bowls. Follow the directions on your package of noodles – there are many different sizes and widths of rice noodles, so make sure you read the directions. For some fresh rice noodles, just a quick 5 second blanch in hot water is all that’s needed. The package that I purchased (above) – needed about 45 seconds in boiling water.
Ladling: Bring your broth back to a boil. Line up your soup bowls next to the stove. Fill each bowl with rice noodles, shredded cooked beef and raw meat slices. As soon as the broth comes back to a boil, ladle into each bowl. the hot broth will cook your raw beef slices. Serve immediately. Guests can garnish their own bowls as they wish.
Tip: I started getting comments of the broth being too greasy — and after 8 pots of testing, I found out why. When I normally make pho broth, I use a combination of knuckle and leg bones, normally with 20% of the bones having the marrow (below photo). When I started increasing the % of bones with marrow – the broth started getting too fatty. I guess too much of a good stuff is not a good thing! The fattiness is easy to remedy. Refrigerate overnight and just discard the layer of fat that accumulates on top. For best results though, keep the bones with marrow to 20%.