The Indo-Chinese base sauce — dried chillies slow-cooked 20 minutes in oil with garlic and ginger. The backbone of all Indo-Chinese cooking. Store-bought is a pale shadow.
Blended Schezwan sauce and slow-cooked Schezwan chutney use identical ingredients but produce profoundly different results. Blending distributes the ingredients but produces no new flavour compounds. Slow-cooking in oil for 20+ minutes causes Maillard reactions between garlic-ginger amino acids and chilli sugars, fully dissolves the capsaicin into the fat phase, and develops complex aromatic pyrazines that raw blending cannot produce. The 20 minutes is not a convenience — it is the chemistry.
Soak chillies 30 minutes in hot water until soft. Drain (save 2 tbsp water). Blend with garlic, ginger and saved water to a smooth fine paste.
Soaking rehydrates cell walls for smooth blending. The saved soaking water contains water-soluble chilli compounds — using it in the blend retains these rather than discarding them.
Heat oil. Add paste. Cook low-medium 20–25 minutes, stirring every 3 minutes until deep brick-red and aromatic. Add soy, vinegar, sugar and salt in last 5 minutes.
As water evaporates from the paste over 20 minutes, temperature gradually rises above 100°C — initiating Maillard reactions between garlic amino acids and chilli reducing sugars. These reactions produce pyrazines and furans that give homemade Schezwan its characteristic roasted-complex depth absent from raw blended versions. Capsaicin fully dissolves into the oil phase, distributing heat evenly throughout.