Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
You have this container. It's upside down with a stick holding it up and a string on the stick. You're going to catch some U2s (like, the band). You put some food under it and wait. Then, out of the bushes comes Bono. He sniffs around for a bit and then goes under the container. You pull! U2 walked (うつわ) right into the trap! Haha!
This vessel is a relic of my mom's.
What should I do? I accidentally broke the container of blowfish that Koichi cherishes.
First you put some rice in a bowl, then you put a hamburger patty on the rice, followed by some gravy, and then an egg on top. Then, ta-da! Now, your Loco-moco is done!