This paper details an integrated inquiry-based mathematics and science method course for preservice teachers designed around STEM problem-based learning. It documents how problem-based learning (PBL) activities supported PSTs' envisioning of equitable approaches for diverse children. The overarching research question was: "How did preservice teacher learning and lesson design experiences within integrated STEM inquiry translate to their vision of equity-based STEM practice?" The data included PSTs course reflections, STEM PBL 5E units, and reflections as they watched recordings of their teaching their units. This facilitated mapping the development of PSTs' vision for equitable teaching across the field mediated experiences in teaching and learning STEM. Our findings revealed how visions of equitable STEM practices emerged from the PST's own experience as being a learner in an integrated STEM environment and from being a teacher who planned and enacted an equity focused STEM unit in a diverse classroom context. The dual teacher-learner experience of the mediated field experience was critically important to provide experiencing and witnessing the high level of motivation during the meaning-making process and provided evidence that rigorous math and science learning is possible in diverse contexts.