How to cope with a lava flooded portal

In minecraft, I built a portal to the nether but whilst I was building a safe haven around my portal in the nether, I excavated a chunk of netherrack and lava poured out and flooded around the base of my portal, killing me. The lava is shallow but it surrounds all sides of the portal.

After resurrecting and teleporting back, I can't seem to place sand in the lava whilst remaining within the portal. As soon as I step outside I die.

In the normal world, I tried constructing a couple of new portals increasingly far away, but they take me back to my lava flooded nether-side portal.

• Is there any way to neutralise the lava before stepping from the portal?
• How far away must my top-side portal be to create a new nether portal?

Do a suicide run. You can place blocks while you're on fire, so do that. Walk into the lava so that you're past the hitbox of the portal and can lay down blocks, then get as many placed before you burn up. If you were careful in placement, you should have a block or three to jump up onto next time.

The problem is the “blocks” that make up the portal itself are under your cursor. All you need to do is inch out just enough so that the middle of your head is outside of the portal surface, but you haven't yet hit the lava, and then you can target the floor under the lava normally. I've tried this and it works (though it's a bit hard to see through the standing-in-a-portal distortion).

(Note that if you're far enough out to touch the lava, you're also far enough out that you're occupying the space a block would, which would also prevent you from placing one there.)

Test info: Minecraft 1.5.2; situation set up in creative mode and tested in survival mode.