For the steak:
1) Using a sharp knife, slice the steak, against the grain and on angle, into thin strips about 2cm wide.
2) In a large bowl, whisk together the thai red curry paste, coconut milk, sugar, fish sauce, and turmeric, if using. Add the beef, mix well, and set aside at room temperature to marinate for at least 1 hr.
3) Preheat an outdoor barbecue.
4) Thread the beef onto skewers, then lightly spray them with oil. Working in batches barbecue the beef, over high heat until just cooked through, about 2 to 4 mins. Transfer the beef skewers to a serving platter and serve with the peanut sauce.
Cook's Note: Slicing meat thin can be tricky. The meat will be much easier to slice if it is chilled in the freezer until firm.
For the Thai Red Curry Paste:
1) Toast the dried chillies in a small dry frying pan over medium-high heat until smoky and fragrant. Transfer to a medium bowl, cover with hot water, and set aside until softened, about 10 minutes. Drain and roughly chop the chillis.
2) Toast the coriander, cumin seeds, and peppercorns in the frying pan over medium-high heat until toasted and fragrant. Transfer to a bowl and let cool slightly. Grind the spices in a spice mill (clean coffee grinder).
3) In a food processor, combine the chillies, ground spices, and all of the ingredients, except for the oil, and puree into a paste. Gradually add the oil with the machine running, and puree until smooth. Store the paste in a tightly sealed container in the refrigerator for up to 1 week.
For the peanut sauce:
1) Stir-fry the coconut cream in a small saucepan over medium heat, until the oil separates and sizzles, about 2 minutes. Add the curry paste and stir-fry until fragrant, about 2 mins.
2) Whisk in the broth, coconut milk, peanut butter, and fish sauce. Bring to a boil over medium-high heat, reduce the heat to maintain a gentle simmer and cook, stirring, until thickened, about 10 minutes. Transfer the sauce to a serving bowl and cool to room temperature. Whisk in the lime juice just before serving.