Tapas are just Spanish meals reduced to small portions, so they can be anything - we've been giving crisps or nuts as a "tapa" many times. They're free and come with your drink, so you don't complain
Trouble is, most of them are high in syns. You could do a potato omelette (tortilla de patatas), using frylight instead of oil. They make big ones then cut them into small slices for the tapa. Or how about experimenting with patatas alioli - garlic-mayo potatoes - but with quark instead of mayo. Low-fat mayo if you want to syn it. Jamon serrano is very low in fat, but I don't know if it's free. Fresh anchovies are another option. Patatas bravas are potatoes with a spicy tomato sauce - again, surely something that can be SW-ed? Olives aren't too bad syn-wise, are they? Cheese (queso manchego) could be a HexA? Albondigas (meatballs) are another popular choice and again, could be made SW by using low-fat mince and Frylight. Mussels with garlic, peppers and onions . . .
or how about if you are having a red day - doing some Calamari or prawns, or meat skewers..
I love the Greek version of Tapas, Meze, which is exactly the same... traditional dishes but just made smaller !! although where is the fun in all that ?????
We had a completely syn free tapas night at home for us and friends, ate too much and were stuffed! It was really sucessful. Best to have it on a EE day so you can enjoy lots of different things
IIRC I made:
albondingas - meatballs in a spicy tomato sauce
patas bravas - cubed 'roast' potatoes with some paprika to spice them up, with a 'mayo' made of fromage frais and paprika
chicken kebab skewers, marinated in lemon juice, oregano and smoked paprika.
squid and king prawns flash 'fried' in garlic and chilli
cubed manchego cheese (very similar to parmesan so used the weight as HA)
large caperberries (with stalks) give you all the saltiness of olives without the syns
spanish tortilla (onion and potato omlette) cut into cubes
You can get squid from the fishmongers (though it will have been frozen, so you cannot re freeze it), but the easiest way is to buy it already frozen in bags of about 500g - most of the supermarkets will sell it frozen (Tesco's certainly does) and it is just as good and it is all prepared for you.