Ask HN: How does an EU resident and a US resident form a company?

What's the easiest way for somebody from the EU to go into business with somebody from the US? Assuming that both are working legally in their respective countries as either freelancers or limited companies themselves?

- Form a separate US company (can a EU resident do this)? - Form a separate EU company (can a US resident do this)? - Use something like Stripe Atlas?

With so many independant contractors on HN, I thought that this might be a situation that somebody has encountered before.