How to foster ideological pluralism in teaching? It is common in Economics to have introductory courses based on one-sided ideological textbooks (e.g. the most famous being this one, ToC here). The problem of course is not the particular ideological orientation they have, but that most of these textbooks explicitly omit alternative ideological readings or understandings of the science. For example, the aforementioned book covers mainly neoclassical economics, and a bit of Keynesianism, amid a wide range of alternative schools of thought. The lack of acknowledgement of this wider picture nudge students to think that the science itself is defined on what the textbook presents. "This is Economics and nothing else".

Naturally, that is a deeply misleading view of a very diverse field, and particularly damaging (in my view) for those just starting to learn the subject.

Given this context, which are the best methods to foster pluralism in teaching, particularly introductory courses?
How refreshing to see someone who recognizes a spectrum of ideas and wants to teach it!

Science in general and economics in particular could be said to revolve around observation of phenomena, theorizing about causes, and research to verify or falsify the theory.

Try addressing topics in this framework: Here's the phenomenon, here are some of the theories to explain it, and here is some research on it which supports / refutes particular theories.  This will provide a model for your students to learn the subject without descending into rote recitation of the professor's favorite dogma.