This puzzle is easy to solve, but difficult to solve.
A good solution is that the method of siege with thin soup boiled with grain did exist in ancient times, which can be a metaphor or a realistic method. For example, red and white things are gold and silver in ancient times and paper money in modern times.
In ancient winter, in order to quickly build fortifications (defense or siege fortifications) and make fortifications firm and complete in an instant, a layer of glutinous rice soup (glutinous rice soup is the most sticky, sticky particles and the like) was often poured on the outside of earth fortifications, which would be very firm and complete, similar to our current high-standard cement. The effect of the fortification looks black and yellow.
It is a metaphor, which means that the explanation of this dream from riddle to riddle is actually a "problem-solving" situation, which means that you encounter a problem or dilemma in reality and need clever methods to solve it, so the mysterious black rice and yellow porridge appears. For your problem, these four words can be used in any way, aiming to attack the city slightly, that is, to solve your problem situation. Black and yellow are two strong color contrasts, mysterious and vast. You must have some ideas to show in your heart, thinking that you can reach some ingenious and magical realm, so you have this dream.