In a microwave-safe dish, add tomatillos, 1/3 of the onion, 1/3 of the garlic, and serrano pepper. Cover with a damp paper towel, and cook in the microwave for 7-8 minutes.

While the tomatillo mixture is cooking in the microwave, place a large pot over medium-high heat, add butter and remaining onion. Sauté for about 5-7 minutes, stirring frequently, until onions begin to caramelize and brown. Add remaining garlic and sauté for about 2 minutes, until fragrant.

While the onions and garlic are cooking, trim unwanted fat from chicken thighs and cut into strips or small chunks.

Transfer the tomatillo mixture to a blender or food processor, add cilantro, lime juice and salt, blend until smooth and add to the pot.

Add stock, green chilis, chili powder, oregano, sliced chicken thighs, and corn to the pot. Let simmer for about 10 minutes, until the chicken is cooked through.

Garnish each bowl with radish, avocado, and chips.