Combine wine, white wine vinegar, and shallots in a saucepan over medium heat. Simmer to reduce to about 4 TBS. Strain out the shallots and discard.
Add wasabi and soy sauce to mixture and reduce the heat. Slowly add butter while stirring until completely mixed. Stir in cilantro and remove from heat. Set aside.
Spicy Ponzu Sauce:
Whisk together all ingredients. Let sit at room temperature for at least 30 mins.
Tuna Steaks
Preheat grill as hot as you can get it. Brush tuna steaks with olive oil. Season with salt and white pepper and place onto the grill.
Grill for 90 seconds then flip and continue grilling for 90 seconds more.