You are asking how to train in overcoming mind's tendency to stereotype and to reify superficial perceptions. Generally speaking, entire Buddhist path is about training in this. Much of the philosophical study (Madhyamaka) and practice of Zen and Vajrayana's higher tantras (Mahamudra and Dzogchen) are aimed at transcending the limits of superficial mind.
Working with a live contemporary teacher adds a practical aspect that is not readily explained in texts. This aspect has to do with application of Buddhist insights to everyday life. The superficial mind with its tendency for stereotyping keeps creating reoccurring patterns in one's personal life. It is by exploring and challenging these patterns that we get to see our superficial mind objectively. This leads to gradual disidentification and eventual freedom from stereotypical thinking.
In my personal experience undergoing this training, there are two parts to it. The first one is explained conceptually, for the student to practice on his own, between the periods s\he meets with the teacher. The second part is traditionally taught by the teacher in-person, without much explanation.
The part that's explained conceptually is a standard instruction on non-attachment. In my "lineage" it goes something like this:
- REMEMBER: every time whenever you feel a negative emotion in response to a real life situation,
- assume the emotion comes from an "attachment" (a traditional word for preconceptions and stereotypes), then
- engage in 5-second introspection to quickly identify the specific attachment, then
- make a silent symbolic gesture of admonishing your ego for trying to protect its solidity, and then
- mercilessly take the attachment away from your ego,
- FINALLY, watch the emotion subside and deal with the situation properly.
The act of giving up your attachment is designed to leave you highly vulnerable - but also much more open to other perspectives and frames of reference. By definition, the more a certain idea is important to you, the harder it is to let go of attachment. Ego is a master of rationalization and to be honest some of its reasons are actually pretty logical and often valid, but in context of this practice all these rationalizations must be ignored, and all attachments must be let go. The exercise gets seriously difficult when it involves dealing with other people over different interests and perspectives, especially when this is a real life or work situation, especially when you are right - but this is exactly what makes this practice so effective.
The second exercise consists of your teacher occasionally pushing you to operate outside of your comfort zone. The normal student's reaction is to indulge in one's egoistic defenses until one day the student learns to get over them and open up to non-preconceptualized activity. This involves enormous creativity on the teacher's part, setting up all kinds of embarrassing situations in which the student is put on the spot and does not know how to react. It's hard to give specific examples since they tend to be very personal. A good Zen master or Vajra master has a talent for endless improvisation of these. The practice is both very painful and very effective for driving the student outside his or her preconceptualization.
In the absence of live teacher my advice is to get creative yourself and start finding ways to put yourself in situations when you do not have a good plan of action. Luckily, modern social life gives endless opportunities for trying one's luck outside one's comfort zone and watching oneself stumble.
Both of these exercises work by forcing the student to lay aside one's preconceived notions, and practice operating in the preconceptual space of "beginner's mind".
It's seems awkward to explain all this in writing, as it is usually presented in a much more pithy and casual style in the middle of real life situations. Despite my limited ability to explain it with clarity, I can't overemphasize the importance of this practice. In my experience, it makes night-and-day difference in one's ability to comprehend and realize true Dharma. Hope it helps.