Use a slice of lime to gently wet the rim of a rocks glass. Dip the rim of the glass in coarse salt, as much or as little as you like. Set aside.
Place the raspberries and lime juice in the Mason jar. Muddle (gently crush) the raspberries until they are completely squished.
Add the simple syrup and orange juice to the jar, then fill it halfway with ice. Screw the lid tightly onto the jar and shake it as hard as you can for 20 seconds. The margarita should be well blended and the ice should be crushed inside the jar.
Fill the salt-rimmed glass with fresh ice. Pour or strain the mixture into the glass. Garnish with a lime wheel and serve immediately.
Notes
Using freshly squeezed lime juice will give your raspberry margarita mocktail the best flavor, but bottled lime juice can be substituted if you're short on time.
Try experimenting with different sweeteners, such as honey, agave syrup, or maple syrup. Each sweetener will impart a unique flavor to the mocktail.
You can use any other berries, such as strawberries, blackberries, or blueberries, which are all great.