Sambal oelek is the plainest and most versatile member of Indonesia's vast sambal family — a coarse, bright-red paste of fresh red chillies crushed with salt and a little vinegar or lime, and nothing else. Rougher and more chilli-forward than a smooth hot sauce, it tastes of pure, fresh capsaicin heat and tang, and serves as a base seasoning that cooks build other sambals and dishes on.