Ideas for blueberry sauce with lemon cake

Blueberry coulis - pronounced cool-eee
Add blueberries and I would suggest also a little bit of blackberries, water, and if want and I recommend, sweet red wine. Reduce (cook) down until syrupy then strain or smush using a potato masher

Mock recipe
8 oz blueberries
3 oz blackberries
2 cups of sugar - granulated
2 cups of water
1 cup of red wine

Cook sugar wine and water until boiling then add berries and cook on med-hi heat until reduced thick enough it coats he back of your spoon.
You can then either run through a sieve to strain the seeds and it gives you a nice and shimmering sleek sauce
Then chill
Or
chill and blend it all together

I know it's popular, but I'm not a big fan of herbs in desserts, so I'd probably use vanilla. Or to give it some kick and lovely color, maybe add a little Creme de Cassis (good to have on hand for emergency Kirs.) A dab of sour cream or creme fraiche on top might be gilding the lily, but in a good way ;)

My personal preference would be rosemary or basil and then definitely put some lemon zest/juice in the mixture to brighten the blueberry flavor. And I second athomeblog's recipe! Also if you need to thicken your sauce, sprinkle in a tiny bit of flour or cornstarch.

You could also try vanilla and very little sugar. Try 3 cups frozen blueberries, 2/3 cup water, 1/4 cup sugar (vanilla sugar, if you have it) and 1 teaspoon vanilla extract. Bring to a boil for a minute or two, then simmer until the blueberries burst and it thickens. Can taste then for more sugar or punch up the vanilla with a bit more vanilla extract.

Tarragon would be yummy--and so would thyme or mint.