Quality interpreting in courts and tribunals requires high competence in language and contextual knowledge, as well as interactional management and ethical reasoning skills. But a cohort of the interpreting workforce in Australia -- particularly those from the so-called "new and emerging" language backgrounds -- has been disadvantaged due to a lack of access to university or vocational training for interpreters. These interpreters, therefore, work in specialised areas such as courts and tribunals with little or no formal training. This paper describes a pilot project that operationalised Optimal Standard 3 of Australia's "Recommended National Standards for Working with Interpreters in Courts and Tribunals" regarding the provision of mentorship to interpreters who are under- or untrained. The project comprised two stages: in Stage 1, interpreters attended a tailored professional development course on legal interpreting; then in Stage 2, a group of thirteen interpreters selected from Stage 1, plus four recruited mentors, participated in mentorship reflecting Optimal Standard 3. The outcomes show the potential applicability and utility of this Standard for its intended purpose. However, for such initiatives to be viable, they require additional support, including administrative and financial resources from the courts and other stakeholders, as well as a rethinking of interpreter employment models.