"Fy hoff fwyd yw bwyd llysieuol."

Translation: My favourite food is vegetarian food.

[JamesTWils]

Could yw also be ydy?

[EllisVaughan]

Yep, they are definitely dialect versions in some instances so I assume they work like that here.

[JamesTWils]

Diolch am eich cymorth.

[bristowwan]

Is llysieuol equivalent to figanaidd then?

[Bronwyn528860]

It is vegetarian (which can include milk and eggs) versus vegan (which doesn't include any animal products).