We've got ours, too, and I think I'm taking curry (a few of us are bringing bigger portions of things) but there's a 1/2 syn roulade on here that's very popular or maybe something simple like total 0%, figs and honey is very lovely and only a syn per tsp of honey (and figs are in season, unlike many of the soft fruits/cherries one might bring to a spring/summer taster)
Or maybe butternut squash chips or the quiche?