Chop and mince the garlic, onion and rosemary so that they are ready to use.
¼ small red onion, 1 garlic clove, 1 tablespoon fresh rosemary leaves
Place the oil and 1 tablespoon of the butter into a skillet and set on a medium high heat on the stovetop.
1 tablespoon oil, 2 tablespoons salted butter
Once hot, add in the onion and garlic. Cook for a couple of minutes til softened. Do not brown it.
¼ small red onion, 1 garlic clove
Add in the rest of the ingredients and stir together.
1 tablespoon fresh rosemary leaves, 1 tablespoon fresh thyme leaves, ¼ cup balsamic vinegar, ¼ cup red wine vinegar, 2 tablespoons maple syrup, 2 cups blueberries, ½ teaspoon salt, pinch black pepper
Bring to a simmer. Let simmer for around 10 minutes, stirring occasionally, until the sauce has thickened and reduced.
Take off of the heat and stir in the remaining 1 tablespoon of butter.
2 tablespoons salted butter
Taste and adjust the sweetness or salt if required.