When my family has porridge for a meal, we always break out the preserved vegetables. I don't know why preserved veges tastes better by itself or with porridge rather than with rice/noodles. There is such a huge selection of preserved vegetables to choose from at the grocery store that it can get intimidating.
I recommend Sing Long Preserved Vegetables (Mei Cai) steeped in olive oil. It is the same preserved vegetables served with braised duck at the Hawker Centre or stir-fried with pork belly at the Mixed Rice Stall, sans olive oil. At just $1.95 a bottle, its also the same price as ordering it at the foodcourt.
AAA Pickled Lettuce $1.50 a bottle. It's crunchy and sweet lettuce stalks steeped in soy sauce. Reminds me of Japanese purple pickles, only you can buy this one at the store and bring home.