Mediterranean dinner party

I love this Mark Bittma recipe: http://cooking.nytimes.com/recipes/1014477-fennel-compote-with-tomatoes-olives-and-fish-or-not

The compote is very flavorful, so perhaps you could serve it as an accompaniment (and not as a main).

And this makes a great appetizer and a beautiful presentation: https://food52.com/recipes/41906-fresh-herb-platter-sabzi-khordan

I served it at a dinner party and it was the dish I received the most compliments on (and it was the easiest to prepare!).

Other than a fish stew or paella, my idea of a showstopper fish dish for a dinner party would be a whole fish either roasted or baked.

The showstopper quality would be the freshness of the fish and its natural flavor rather than than sauce. The Japanese know this through and through.

I'd serve the whole fish very simply, garnished with some lemon wedges or slices. On the side, I'd offer a few sauces: like aioli, pistou, maybe gremolata or other herb based condiments.

Just to clarify - I'm not fussy if my dishes are authentically Mediterranean. Just looking for elegant, showstopper seafood dishes with Mediterranean flavours.

I don't associate oysters with the Mediterranean. Oysters are better from colder waters like the north Atlantic or north Pacific.

Gougeres -- while delicious -- are definitely not Mediterranean. They are most closely associated with Burgundy and are commonly made with mountain cheeses like Gruyere or Emmentaler. Something like herbed olives, crostini, bruschetta would be a far more Mediterranean appetizer.

Your Guardian Chef is correct: salmon is not a Mediterranean fish. Sea bass, flounder, mackerel and John Dory would be more typical fish species.

I'm not sure how open-minded your guests are, but if it were me I like to make something that is sort of a combination of octopus salad and the well known Galician dish Polbo à Feira. Basically, buy the largest octopus arm you can find (fresh or frozen).
You can either put in a slow cooker for 4-5 hours, simmer it in water or seafood/vegetable stock for 45 mins, or seal it in a vacuum/sous vide bag and simmer at 190F for 3 hours.

If you want it to be more like a salad - slice arm into rounds then chop into rounds and chop into thirds or sixths depending on the size of the round, then toss with your best olive oil, minced garlic, medium dice red onion, chopped green or brown olives, chopped flat parsley, the leaves of two sprigs of thyme, and the juice of one or two lemons and its zest, enough to coat. Season with S/P to taste and let rest 30 mins to 1 hr in the fridge before serving.

If you want it to be served more like tapas - slice the octopus arm with your sharpest knife or even a good bread knife to about 1/8" thick rounds if it will hold. Place nicely on a bed of lemon slices or arugula, drizzle with olive oil and sprinkle with coarse sea salt and Spanish pimentón or paprika.

Simple and fresh but still a bold dish to impress at the table.

Some of the menu items I've been considering have been:
Oysters mignonette
Gougeres
Salmon baked with fennel
Prosciutto wrapped figs
Miniature spanakopita with preserved lemon hummus and tzatziki

a paella like dish with seafood only, ratatouille, green salad or sliced tomatoes with vinagrette and that is one colorful table.