Line an 8-inch loaf pan with parchment paper.

Combine the raspberries and lemon juice in the bowl of a food processor. Process until pureed. Pour the juice through a sieve to strain out the seeds, if desired.

Whisk in the simple syrup.

Pour the mixture into the prepared tin. Cover & freeze until almost solid.

Scoop or scrape the frozen sorbet into the bowl of a food processor. Pulse until creamy, but still solid. Serve immediately, or transfer back into the pan, and freeze until ready to serve.

Alternatively, once the simple syrup has been whisked in, you can pour the mixture into a frozen base for an ice cream maker, and churn for 20 to 25 minutes, then freeze for at least 2 hours before serving.