Preheat the oven to 200°. Rub the steaks with olive oil and sprinkle them with the hot paprika, rubbing to coat. Season the steaks with salt and transfer them to a small roasting pan. Roast for about 1 1/2 hours, until an instant-read thermometer inserted in the thickest part of the steaks registers 125° for medium-rare.
Meanwhile, in a mini food processor, puree the miso with the soy sauce, lime juice and zest, mustard powder, orange juice, kecap manis and sweet paprika.
In a medium saucepan, melt the butter. Add the miso mixture and whisk over moderate heat until smooth and creamy, about 1 minute. Keep warm over low heat.
In a skillet, heat 1 tablespoon of olive oil. Add the steaks and cook over high heat, turning once, until browned, 4 minutes total. Transfer the steaks to plates and serve with the citrus-mustard butter.
Kecap manis is a sweet Indonesian soy-based sauce sold at Asian markets.