Wrong - уснаас хойш, correct - ууснаас хойш. Literal meaning: I ate nothing after drinking morning tea. Meaning: I ate nothing after morning tea / I ate nothing after breakfast. Note: "өглөөний цайгаа уух" literally means "to drink a morning tea", but the meaning usually is "have breakfast". In case I want to say that I only had a cup of tea for breakfast, I'd say: Би өглөө аяга цай л уусан / Би өглөө ганц аяга цай л уусан.