Blueberry Mustard Sauce -- great with pork, chicken, even salmon

For my upcoming birthday, my BFF gave me a pile of blueberry products she got up in Michigan (a.k.a. blueberry heaven) -- she knows it's my favorite fruit.
One of the items was blueberry mustard, which set me on a quest to use some late-season berries in a somewhat unusual way.
If you don't have blueberry mustard, that's fine -- just use regular mustard in this recipe.
For company, I had it with grilled pork tenderloin, served here (in photo) on a bed of greens, mixed veggies and grains. The sauce received rave reviews!
I had enough leftover to sauce another dish; I popped it in the freezer for now and will likely use it with chicken or fish in a couple of weeks.

Recipe: Grilled Pork Tenderloin with Blueberry Mustard Sauce Serves 4
Ingredients:
One large pork tenderloin, about 1 1/4 pounds
3 T minced garlic
2 T canola oil
Salt and freshly ground black pepper

1 medium to large shallot, finely chopped
2 T olive oil
1 1/2 pints fresh blueberries
1/4 cup dry white wine
3 T mustard (or blueberry mustard)
Juice of 1/2 lemon
2 T sugar
Salt and freshly ground black pepper

Instructions:
In a flat bowl large enough to hold the tenderloin, mix together garlic and canola oil. Season pork with salt and pepper and place in bowl. Turn pork to coat all sides with garlic mixture. Cover and refrigerate for at least one hour and up to 6 hours. Remove pork from marinade and scrape off garlic bits (they will burn when grilled).
Preheat a grill until hot. Cook pork on medium-high heat to desired level of doneness.
While grill is heating, make the sauce:
Heat the olive oil in a medium frying pan and add the shallot. Stir and cook for about 3 minutes, until shallot starts to soften.
Stir in blueberries, wine and mustard. Cover and reduce heat to low. Cook for about 5 minutes, then uncover and increase heat to medium-high, letting mixture boil and give up some of its liquid. Add lemon juice, sugar and seasonings. Taste and adjust as needed, adding more sugar if you think it needs it.

Let pork sit on a cutting board for a few minutes after you remove it from the grill. Slice pork thickly (about 1 1/2 to 2 inches) and arrange on a platter. Top with a small amount of sauce, then pass the rest of the sauce in a gravy boat at the table.