Preheat oven to 350°F (175°C) and lightly grease a 9-inch tart pan.
Combine rolled oats, walnuts, and salt in a food processor and pulse until a fine crumb consistency is achieved.
Add maple syrup and melted coconut oil to the processor, pulsing until the mixture holds together when pressed.
Press the crust mixture firmly into the bottom and up the sides of the tart pan.
Bake for 10 to 12 minutes until the edges are golden brown, then remove from oven and let cool completely.
In a medium bowl, whisk together the Greek yogurt, honey, and vanilla extract until well combined and smooth.
Spread the yogurt mixture evenly over the cooled tart crust using a spatula.
Arrange the strawberries and blueberries on top of the yogurt layer in a decorative pattern.
Refrigerate the tart for at least 2 hours to allow the yogurt to set before slicing and serving.
Keep refrigerated until ready to consume.