Preheat oven to 350°F. Pat chicken thighs dry using a paper towel. Sprinkle flesh side with coriander, kosher salt, and pepper.
Heat olive oil in a large skillet over medium-high heat. Cook chicken, skin side down, undisturbed, until thighs release easily from pan, about 4 minutes.
Continue to cook until the chicken is golden brown, about 5 minutes more. Transfer chicken to a plate.
Add leeks and garlic to the same skillet as the chicken and cook, stirring occasionally, until slightly softened, about 3 minutes.
Next, add lemon zest and cook, stirring, until fragrant, about 20 seconds. Pour in the white wine, scraping up any brown bits stuck to bottom of pan with a wooden spoon. Cook until wine is almost completely evaporated, about 3 minutes.
Add chicken broth and bring to a simmer. Return chicken to skillet, arranging skin side up. Transfer skillet to oven; roast chicken until cooked through (165 degrees) about 15–20 minutes. Transfer chicken to a plate.
If using fresh peas, cook in same skillet over medium heat until tender and bright green, about 3 minutes. If using frozen, cook just until warmed through, about 1 minute. Toss in mint; season with more salt if needed. Arrange vegetables and chicken in a large shallow bowl or on a platter and add radish if desired.