The Decoding the Disciplines paradigm posits that each discipline has unique mental operations – often invisible to instructors due to their own expert blind spots. If the nature of these operations is not made explicit to students, they are likely to develop learning bottlenecks that could prevent them from mastering key disciplinary practices – such as the ability to reliably work through the chain of reasoning necessary for efficient source code comprehension (SCC). This study seeks to assist instructors to help novice programmers reliably think and work their way through a long chain of reasoning to efficiently comprehend a piece of source code. We followed a narrative approach where data was collected through decoding interviews with five expert programming instructors. Several SCC strategies were identified, but only the seven key ones were used to devise a step-by-step framework for efficient SCC. Our findings aim to create awareness among instructors regarding the explicit mental operations required for efficient SCC.KeywordsSource code comprehensionexpert programming instructorsdecoding the disciplinesdecoding interviewcomputer science educationbottleneckCS1