Prepare the spice blend by mixing the curry powder, turmeric, cumin, ground coriander seeds and cinnamon in a small bowl.
Heat the oil in a large skillet. Add the onion and saute for 4 minutes over medium heat..
Add the diced apple and cook for another 2 minutes.
Add the minced ginger and garlic and stir.
Add the spice blend to the onion mixture and stir constantly as it cooks for 2 more minutes.
Add the flour and stir constantly as it cooks for 2 minutes. Scrape the bottom of the pan to prevent burning.
Gradually add the chicken stock, stirring constantly to prevent lumps from forming.
Add worcestershire sauce, sugar, tomato puree and stir. Season with salt and pepper.
Bring the sauce to boiling point, stirring constantly. Then reduce the heat to low and simmer the sauce for 15 minutes.
Turn the heat off, and allow the sauce to cool slightly before blending. When cool enough add the sauce to a blender or food processor and blitz until smooth.
Return the sauce to the pan over medium heat. Add golden raisins if desired.
Serve hot with a side of chips or french fries.
Achieving a glossy, clinging consistency in traditional chip shop curry sauce depends entirely on how thoroughly the flour is cooked in fat before the liquid arrives. Without this fundamental step of making a quick blond roux with the oil, flour, and spices, the starches will remain raw and clump instantly upon contact with cold stock. Developing this emulsion properly requires holding the heat at a steady medium and scraping the pan continuously for precisely two minutes until the mixture smells toasted and nutty. Culinary traditions across the British Isles have long embraced this style of spiced gravy, originally adapted from colonial trade routes into regional comfort food served over thick-cut fried potatoes. Beyond its initial preparation, the sauce benefits immensely from resting overnight in the refrigerator, where starches retrograde and allow the sharp notes of coriander, cumin, and turmeric to mellow into a cohesive depth of flavor.
Mastering the Spice Bloom
Raw spices contain volatile oils that must be unlocked through direct contact with heated fat rather than liquid. Introduce the curry powder, ground cinnamon, and cumin directly to the sautéed onions and diced apples alongside the oil, stirring constantly for two minutes until the aromatic compounds release their heavy fragrances into the kitchen. This technique prevents the powdery, chalky mouthfeel that ruins many amateur attempts at gravies thickened with dry starches. Ensuring the pan temperature does not spike too high during this phase protects the delicate garlic and ginger from turning bitter before the stock is added.
Achieving Silkiness Through Blending
Pureeing the simmered mixture after fifteen minutes of low heat transforms chunky fruit and aromatics into the characteristic velvety coating required for proper chip coverage. Let the cooked sauce cool slightly before transferring it to an upright blender, filling the vessel no more than halfway to prevent pressure explosions from hot steam. Blitz the contents on high speed for at least sixty seconds until completely uniform, then return the liquid to the stovetop for a final adjustment of seasoning with salt and pepper.