|Complete A Train to Catch||15||Sanctuary (Lilith)||2333 XP, 4 Eridium|
Some bandits are mining some Eridium in Tundra Express and Lilith wants you to go kill them. The area isn't hard to find and once you're there, you can go ham on the miners there, which include Rats, Marauders, Goliaths and even Nomads. Kill ten of them and Lilith will order you to find and kill the head miner, who is named Prospector Zeke.
Getting to him is a little tricky and will require a bit of platforming. Look for the conveyor belt with the pistons hitting it, then jump onto it from nearby platforms. Run through the "gauntlet" of pistons and drop onto another conveyor that will lead to the top of the area with Zeke. Zeke is a Nomad and he'll have some other bandits there with him. Kill Zeke, loot his ECHO, then turn in the mission to Tiny Tina.