Rau mong toi, or according to Cook's Thesaurus, Vietnamese spinach (slippery greens, saan choy, etc.), can be found in any Asian market, and is great with seafood. We usually have it with shrimp, but I was craving clams, and found that clams work just as great. Cherrystone or littleneck clams work better than smaller clams, because you have that bite into the juicy, non-overcooked clam meat. Such a good soup for the cold winter day! —matchaflan
Vietnamese spinach (normal spinach works fine)
Clean the clams, fill a medium pot with water enough to just cover the clams. Boil till the clams just open, take out right away and separate the meat and the shell. Drain the water that comes out back into the pot and discard the shell.
Roughly chop up the spinach and boil with the clam water, salt to taste. Should take only 5 minutes! Once it's cooked, turn off the heat and add the vinegar. Salt to taste.
Chop up the garlic and saute with neutral-tasting oil until fragrant. Put in clams and very quickly saute with the garlic.