Place the strawberries in a blender; cover and process until pureed.
Add lemon juice and sugar; cover and process until blended.
While processing, gradually add vinegar and oil in a steady stream; process until thickened.
Stir in poppy seeds.
Transfer to a large bowl or jar; cover and store in the refrigerator.
Emulsification Basics
Fresh fruit purees lack natural lecithin, meaning oil and fruit juice separate quickly without mechanical help. Pouring the neutral oil in a slow, continuous stream while the blender motor runs at high speed forces fat droplets to suspend evenly within the strawberry puree. Adding cider vinegar and lemon juice simultaneously provides the necessary acid to balance the sweetness while keeping the emulsion intact longer.
Texture Control
Thawing frozen strawberries thoroughly before processing prevents ice crystals from diluting the dressing and ruining the viscosity. Pureeing the berries completely smooth before adding other liquids ensures the final product coats greens cleanly instead of pooling at the bottom of the bowl. Folding poppy seeds in by hand at the very end preserves their distinct crunch.
Equipment Options
Stand blenders create the vortex required for smooth purees, though immersion blenders work efficiently inside deep glass mason jars. Straining the finished liquid through a fine-mesh sieve removes any lingering seeds for a glossy, professional finish.