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're eating a meal... MMmm, delicious! What are you eating? Well, it's a Mesh (めし) net. Taste the mesh net. It tastes terrible. This is a bad meal. Feel it in your mouth. It's weird and meshy.
Oh no. I forgot to cook rice.
Koichi would rather work for Tofugu than eat.
Those were some really stinky-smelling meals! I never want to go back to prison.