Step 1

Heat a medium heavy skillet, preferably cast iron, over medium.

Step 2

Meanwhile, place chicken thighs, skin side down, on a work surface. Using a paring knife and working one at a time, cut a 1/2"-deep slash along both sides of thigh bone. This will help the thighs cook a little more quickly and evenly. Add oil to pan.

Step 3

Season chicken on both sides with salt, then sprinkle all over with mustard seeds and fennel seeds, patting to adhere. Place chicken in skillet skin side down, and cook, undisturbed, until skin is very deeply browned and crisp and chicken is about 75 percent cooked through, 18–20 minutes. Some seeds will end up in the pan, which is fine as they will flavor the oil. Spoon out any that are burning. Turn chicken and cook on second side until just cooked through, about 4 minutes longer. Transfer to a platter and let rest 10 minutes.

Step 4

While the chicken rests, toss cucumbers, watermelon radish, red radishes, scallions, vinegar, and a pinch of salt in a large bowl.

Step 5

Cut chicken off the bone, then slice crosswise into 1 1/2"–2" pieces.

Step 6

Gently toss chicken and pita chips into salad. Taste and season with more vinegar and/or salt if needed.