Didn't find a one-stop answer to this question, so here it is:
"How do I POST JSON to an ASP.NET MVC controller?"
It's actually quite simple. Follow the following steps.
1. Create a model to represent the data structure you want to POST
2. Create a controller method to represent the endpoint you want to contact
3. Create the following jQuery call to make an AJAX call from the frontend to the backend
You can return a PartialViewResult from the controller, and as long as the jQuery AJAX call expects html it will be done.
Hope this helps someone.