For the marinade and chicken: Combine the lemon juice, garlic, oregano, coriander, 1/4 cup olive oil, salt, MSG, and pepper in a blender or the cup of a hand-blender and blend until roughly emulsified. It should taste quite salty. Place the chicken in a bowl and pour half the marinade over it, reserving the rest. Massage the marinade into the chicken so all surfaces are coated. Cover and refrigerate at least 1 hour and up to 4 hours (see note above).
For the chicken: Add 1 tablespoon olive oil to a large skillet over medium-high heat until the oil shimmers. Add the chicken in a single layer. Cook without moving until well browned, about 5 minutes. Flip and cook until the second side is browned and the chicken registers at least 165°F / 74°C on an instant-read thermometer, about 5 minutes longer. Reduce the heat if the browned bits in the pan threaten to burn or smoke excessively. Transfer the chicken to a plate and reserve the pan with the fat and browned bits.
For the rice: Add the butter to the skillet and set it over medium heat. Add the cumin and turmeric and cook until fragrant, about 30 seconds, scraping up any browned bits from the bottom of the pan. Add the rice and stir to coat in the fat. Cook, stirring, until the grains look glossy, about 1 minute. Add the chicken broth, season lightly with salt, pepper, and MSG, and bring to a boil. Reduce to a bare simmer, cover, and cook 15 minutes. Turn off the heat and let sit, covered, 10 minutes more.
Meanwhile, make the white sauce: In a bowl, whisk together the mayonnaise, yogurt, sugar, vinegar, lemon juice, salt, MSG, pepper, and parsley or dill until smooth (see note above). Taste and adjust seasoning. The sauce should be tangy, slightly sweet, and a little salty.
Chop the chicken: While the rice cooks, chop the chicken into small pieces, about ½ inch (1 cm) across. Toss with the reserved marinade and any juices from the plate. When the rice is cooked, fluff it with a fork and transfer to a large serving bowl or platter.
Reheat the chicken: Return the chopped chicken and its marinade to the same skillet over medium-high heat. Cook, stirring and tossing constantly, until the marinade reduces and coats the meat, a few minutes. Taste and adjust, seasoning with salt, pepper, MSG, and/or lemon juice. Scatter the cooked chicken over the rice. Serve immediately with chopped vegetables, white sauce, and hot sauce.