I tried this "substitute for caper sauce" expecting a quick, simple sauce. I found that it is delightfully unpretentious, a stark contrast to the fancy emulsions I've made in my career. It was a challenge to keep my butter melted without scorching it — a true test of patience and low heat management. I was particularly struck by the instruction to boil the parsley until it turned a "bad colour". This yielded a surprisingly earthy, muted flavour that I didn't expect from such a simple ingredient. The vinegar cut through the richness of the butter beautifully, creating a harmonious balance of flavours. This sauce would be a wonderful addition to a weeknight cook's repertoire. It pairs excellently with simply grilled fish or roasted chicken, adding a touch of vintage charm to modern meals. The best part? It's ready in a flash, making it an ideal last-minute sauce to have up your sleeve. The key to success? Don't rush the butter.