The comments are coming in that explosive weapons are not
required for this achievement. Elytron missiles, syndicate AoE effects, Kulstar, Rhino Stomp have all been confirmed as working. Before continuing on if you don't have an explosive weapon, check the comments in case I haven't caught up and there's an easier way. I'm maintaining the original solution for explosive weapons as is, though if you go for syndicate effects or Warframe abilities, you may want to use a lower level map.
The three easiest weapons to get this are Tonkor, Penta, and Ogris. Ogris is a clan tech weapon that requires Detonite Injectors and Forma, so the other two are significantly easier to get.
Next comes modding it up! If you absolutely, positively want to do this in one shot, you'll likely need a catalyst. At basic, put Serration and elemental mods on. I would opt for fire and ice to make the Blast element. If you have it, Split Chamber acts as another Serration, and Firestorm increases the blast radius.
As for level, while any Dark Sector Defense will work, I would suggest a higher level one. I found the cryopod hangs around longer on higher levels when you aren't actively defending it. I used Sechura on Pluto, but this is particularly late game, so whatever the highest one you can manage. Put it on Solo so no one will bother you.
Warframes, ideally you'll want Loki so you can stay invisible while the infested crowd around the cryopod. If not, take a tank like Rhino, Valkyr, or Frost. Before jumping in the ring that starts the waves, find a high up spot that has a good view of the cryopod. If you need to get higher, bullet jump with
Jump down and start the wave, but clear the first wave yourself. I could only get 7-8 crowding at first, then the explosive runners would explode. Any time after wave 2, you'll see enough enemies for a well placed grenade or rocket to kill everyone.
Cackling at the explosion is optional, but recommended.