Oooh, good question... I'm currently working on a specialised node that uses OAuth 1.0a inside. Because of other needs I'm making it a contribution node rather than doing it in the flow. If you give me a bit I'll see if it can be done directly with the http request node, but chances are that you might either need to include an npm library through the globalFunctionContext (I'll explain in a bit), or rely on a contribution node that does this.
Okay, I took a quick look. Since I've implemented OAuth 1.0a a couple times from scratch in different programming languages, I know the details you don't want to be aware off if you prefer staying sane
While it's not directly supported by the HTTP Request node, you can do it yourself using the
Authorization header, but I would not advise that. I've just seen this node in the flows library,
I've never used it before, but I took a quick scan through the code, and it looks to be decent. I'm using a different oauth library in the back myself, but this one I've seen before, just not my preferred option if I'm working on nodes myself. I think it might work for your needs, but if you need further help setting it up, just type @afelix in a post and I'll see if I can help you any further. It's a generic node, but all the documentation and examples refer to twitter, so that can be confusing.