In a small bowl whisk together zest and juice from the orange, lemon and lime. Mix in the soy sauce, olive oil, sesame oil, shallot, garlic, parsley, ginger and black pepper.
Place tuna steaks in a resealable plastic bag. Pour marinade over and seal. Let stand at room temperature 10-15 minutes and up to 30 minutes.
Heat oil in a large skillet over medium-high heat. Pat excess moisture from tuna steaks with paper towels. Place in skillet and sear uncovered for 1 minute. Carefully flip tuna steaks over and sear for 1 minute more.
Transfer to a cutting board and thinly slice the tuna.
Cooking time can vary significantly depending on the tuna's thickness and temperature of the heat source on a stovetop. This is a general guideline when cooking 1 ½-inch thick tuna steaks uncovered on medium-high heat per side: Rare = 1 minute, Medium Rare = 1.25 minutes, Medium = 1.5 minutes, Well Done = 1.75 minutes.
How to Grill
Make sure the grates are clean and oiled so the fish doesn’t stick. Preheat on medium-high. Pat fish with paper towels to remove excess marinade and avoid flare ups. If your rig exceeds 500 degrees F, you’ll only need to grill each side 30-45 seconds to achieve seared, rare doneness.
Place any leftovers in an airtight container and refrigerate. Rare tuna should be enjoyed within 2 days. If you happened to overcook the tuna, we've all been there. Give yourself a break and turn that well done tuna into the best tuna salad ever.