"Their hunt the roast vegetable sauce": can you parse this?

I had to read it a couple of times before it made sense, but the meaning is

Their 'hunt the roast vegetable' sauce.

In other words, Sainsburys claim that their sauce has many more pieces of vegetable in it than their rivals' sauces have.

They are implying that the competition's sauce has so little roast vegetables, you practically have to hunt around in the sauce to find any.

Their Roast Vegetable Sauce.

vs

Our Roast Vegetable Sauce.

Their "hunt for the roast vegetables because they're so rare" Roast Vegetable Sauce.

vs

Our "clearly has roast vegetables, you can tell without having to hunt for them" Roast Vegetable Sauce.