For the fried rice: Place stock or water and rice in pot, bring to a boil, reduce to low simmer and cook 15 to 17 minutes to tender. Line a small baking sheet with parchment, spread rice on parchment and throw tray in freezer or bottom shelf of fridge to quick-chill.
Heat a large nonstick skillet over medium-high to high heat with 2 tablespoons truffle butter. When butter melts, add maitake mushrooms or mushroom blend and cook until brown and crisp, 7 to 8 minutes. Add leeks, season with salt and pepper and toss 2 to 3 minutes more. Add sherry and cook until it evaporates, 2 to 3 minutes; remove from heat.
To fry rice, heat another large nonstick skillet over medium-high heat, add remaining 2 tablespoons truffle butter and when it foams, add rice and peas and season with salt and Sichuan pepper. Press and occasionally turn every few minutes to crisp the rice in places and soften the peas. Add half of the mushroom and leek mixture and toss to combine. Reserve the remaining mushrooms.
For the salsa verde: Heat a large cast-iron skillet over medium-high heat, add half a turn of the pan of oil, then add shishitos and blister peppers, tossing, 3 to 4 minutes. Remove to platter and sprinkle with flaky salt. Place 7 to 8 of them (about 1 cup) in food processor. Reserve remaining shishitos.
To food processor with the shishitos, add shiso, mint, anchovy fillets, garlic, shallot or scallions, soy, Worcestershire and yuzu or lime juice. Pulse to process then turn processor on and stream in remaining 1/4 cup oil. Remove sauce to small bowl.
For the steaks: Take steaks out and bring to room temperature on a gel board. Season with salt and pepper.
Heat cast-iron pan over medium-high heat, add a little more oil for the steaks. Cook steaks 7 to 8 minutes, turning occasionally, for medium, a minute less for medium rare.
Let meat rest and slice against grain. Serve with salsa on top and shishito alongside. Top truffle rice with remaining mushrooms, radishes and chives if using.