No vegetable starts with qux. The leaf and the root of the ullucus are an edible vegetable.
As for q, there is quinoa, which is a grain, so I suppose that might be classed as a vegetable.
Voavanga
Vanilla
Velvet Tamarind
Xigua
Xylocarp
Ximenia
Quince
Quenepa
Quandong
· xigua
xigua
Jaffa Orange xylocarp - Hard Woody Fruit
A fruit that begins with s is a starfruit! I LOVE THEM!
· uvilla
zucchini
iceberg (lettuce)
· uvilla
· nectarine
· youngberry
Spinach
grapes
Yam.