Whisk buttermilk, milk, and sourdough starter together.
Butter sides of baking dish (I use this souffle dish), or line with parchment paper.
If using an electric cooker, such as an Instant Pot, set to high for 50 minutes. Or if using a stove-top cooker, bring to high pressure and maintain pressure for a cook time of 50 minutes.
100% Whole Grain Sourdough Boston Brown Bread {Instant Pot} https://traditionalcookingschool.com/food-preparation/sourdough-boston-brown-bread-instant-pot/?utm_campaign=autoblog&utm_source=blog&utm_medium=bloglink&utm_content=100%25+Whole+Grain+Sourdough+Boston+Brown+Bread+%28in+the+Instant+Pot%21%29