Pomelo. Treat like an orange or a grapefruit?
I'd say grapefruit, but let your taste guide you.
I haven't had one in a while, but if I remember correctly the membrane is bitter like a grapefruit.
Peels like an orange (thick skin), can be separated into segments like an orange, tastes much more like a grapefruit - although I've enjoyed pomelo that was much sweeter than any grapefruit I've eaten. It is also uniquely dry - usually I open each segment, remove and discard segment skin/membrane and enjoy the fruit on salads.
Pomelo is actually a cousin to the grapefruit (an older cousin actually). Its skin is much less bitter than grapefruit. In fact, I'll be posting a recipe using pomelo, I hope, this weekend. ;o)
it's more grapefruity, though significantly drier, especially at the membranes. i cut mine into segements leaving the tough membrane behind. i'm always astounded by how much peel and pith there is in relation to how much edible fruit it yields.
Closer to grapefruit. Actually if you section it, it matches well with sliced fennel.