For the strawberry chia jam, heat the frozen strawberries in a small pot, add the maple syrup and let them cook on medium heat until soft. Mash them with a fork, add the chia seeds and give it a quick mix. Take the pot off the stove and let it sit for about an hour to thicken.
Pre-heat oven to 360°F/180°C.
In a mixing bowl, combine all the dry ingredients for the muffin base, whisk, then add in the wet ingredients for the muffin base and whisk again until it's a smooth batter.
For the peanut butter streusel: Combine the peanut butter, flour and sugar in a bowl and mash and whisk with a fork until it's nice and crumbly.
Fill the muffin batter in muffin wrappers or use a lightly oiled muffin pan. Top with about 1 teaspoon strawberry chia jam per muffin and press it into the batter a bit. Sprinkle the peanut butter streusel on top. Bake the muffins in the oven for about 20 minutes until golden. Let them cool off a bit before enjoying them!
*Coconut vinegar is mild vinegar which I prefer for my baked goods. You can substitute it with apple cider vinegar for example.