I'd recommend applying to the postings on HN's Who's Hiring thread, especially if you can talk with the founder. Since they will gain value from hearing of your

I'd recommend applying to the postings on HN's Who's Hiring thread, especially if you can talk with the founder. Since they will gain value from hearing of your past four year's experience that might be a good opportunity to showcase your fit, since you have been in the startup trenches very recently.