Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 450 degrees. Pat chicken dry with paper towels; rub each chicken leg with a drizzle of oil and season all over with salt, pepper, and 1/2 tsp Herbes de Provence (1 tsp for 4; we sent more). Place skin sides up on one side of a baking sheet. Bake on top rack for 20 minutes (we’ll add more to the sheet then).

Meanwhile, wash and dry all produce. Dice potatoes into 1/2-inch pieces. Zest and quarter lemon (quarter both lemons for 4 servings). Mince chives. Pick tarragon leaves from stems; discard stems and mince leaves until you have 2 tsp (4 tsp for 4). Mince or grate 1 clove garlic; leave remaining clove whole.

Place potatoes and whole garlic clove in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes. Reserve 1/2 cup potato cooking liquid, then drain and return potatoes to pot. Cover to keep warm.

Once chicken has roasted 20 minutes, remove baking sheet from oven. Toss green beans on empty side of same sheet with a large drizzle of olive oil, salt, and pepper. (For 4 servings, leave chicken roasting and toss green beans on a second baking sheet; roast on middle rack.) Return to oven until green beans are tender and chicken is cooked through, 10-12 minutes more. Toss roasted green beans with almonds and lemon zest to taste.

Meanwhile, in a small bowl, combine mustard, tarragon, half the chives, and as much minced garlic and lemon juice as you like. Stir in 1 TBSP olive oil (2 TBSP for 4 servings). Season with salt, pepper, and a pinch of sugar.

Mash potatoes with sour cream and 1 TBSP butter (2 TBSP for 4 servings) until smooth, adding splashes of reserved potato cooking liquid as needed. Stir in remaining chives and season with salt and pepper. Divide chicken, green beans, and mashed potatoes between plates. Spoon dressing over chicken. Serve with any remaining lemon wedges on the side.