Preheat the oven to 350 degrees F. Add a tablespoon of olive oil to a cast iron skillet. Place the tomatillos trimmed side down. Roast for 10-15 minutes, until slightly sizzling and lightly golden brown. Transfer to the jar of a food processor, along with yellow onion, juice from 1 lime, serrano pepper, handful of cilantro and a few pinches of salt. Blend until pureed and set aside.
To a small pot, heat a few teaspoons of olive oil over medium heat. Add the onion and cook until translucent, about 2-3 minutes. Place the garlic atop and cook until fragrant, an additional minute. Pour in the rice, vegetable stock, tomato paste, cumin and salt; mix until completely combined. Cover and cook for 10 minutes, or until the liquid is dissolved and the rice is completely cooked.
In the cast iron you used to roast the tomatillos (we're about minimal clean-up in these parts), heat a few teaspoons of olive oil over medium heat. Add the slices of plantain, a pinch of salt and cook on both sides for about 1-2 minutes, until slightly golden brown. Remove and set aside. Add the swiss chard, red wine vinegar and a pinch of salt. Cook for about 1-2 minutes, until wilted.
To assemble the bowl, add the rice to the bottom of a bowl, top with the slices of plantains, wilted swiss chard, scoop of black beans, few slices of radishes and a spoonful of tomatillo salsa.