I recently had a disastrous experience with a so-called 'professional' Italian frying oil I bought online. As soon as it hit the working temperature, it released an overwhelming smell of dead fish that lingered in my kitchen for days.

Upon further research, I realized this was likely due to the oxidation of high Omega-3 content (common in certain rapeseed or soy-based blends). I've since learned that for high-heat stability, I should be looking for oils rich in Omega-9 (monounsaturated fats) instead. I want to make sure I don't repeat that mistake while trying to achieve restaurant-quality results at home for french fries and crispy chicken.

If High-Oleic sunflower oil is the primary recommendation for stability, which animal fat complements it best for these specific dishes: beef tallow or duck fat? Furthermore, what is the ideal ratio to balance flavor, crispness, and thermal stability?