Culturally sustaining pedagogies have encouraged scholars to reimagine and rebuild justice-oriented classrooms across context and disciplines and provide opportunities for students to reclaim their ways of knowing and doing in schools. In this study, we seek to contextualize culturally sustaining teaching practices in integrated science and engineering middle school classrooms. In collaboration with Mrs. Johnson, a veteran science and science, technology, engineering, and mathematics (STEM) middle school teacher from the Midwest, this study draws on culturally sustaining pedagogy to understand the experiences of Mrs. Johnson in teaching a diverse middle school. This study also brings sociotransformative constructivism into our conversation to situate Mrs. Johnson's positional identities, the ways in which she enacts her reflexivity, and power in considering how culturally sustaining classrooms are cultivated. Using a narrative inquiry and case study approach, we utilized narrative interviewing to generate stories in making meaning of Mrs. Johnson's lived experiences. We applied thematic narrative analysis to develop three narrative threads, highlighting Mrs. Johnson's intentionality nurturing space for students to cultivate multiple epistemologies and disrupting the status quo in science classrooms. Our study illuminates a complex narrative such as the intentionality of making multiple epistemologies explicit in learning science and engineering and the required racial reflexive work for cultivating a culturally sustaining and student-focused STEM classrooms. We also highlight challenges Mrs. Johnson faces as she integrates students' lived experiences and alternative ways of knowing and doing in science and STEM teaching.