Prawn and avocado salad with spiced tomato dressing

1.For spiced tomato dressing, heat 2 tbsp olive oil in a large frying pan over high heat, add tomatoes and fry, tossing occasionally, until scorched and softened (4-5 minutes). Add garlic, rind and vinegar, remove from heat and transfer to a blender. Add remaining ingredients, blend until smooth, season to taste and refrigerate in an airtight container until required. Dressing will keep for up to 5 days, taste before using and brighten with a squeeze of lemon juice if necessary.

2.Arrange prawns, avocado, cos and celery on a serving platter, season to taste and drizzle lightly with extra-virgin olive oil, then dressing to taste, scatter with celery leaves and watercress and serve.