When two notes are tied together, the second one is not picked, which I understand when they're on the same string, but what happens when they aren't?

If I'm going from an F to a G or a D to a E, how do I get the sound from the second note that's now on a separate string?
Re-finger it so the first note is on the right string.

Or hammer-on from nowhere, either are good.
R.I.P. My Signature. Lost to us in the great Signature Massacre of 2014.