Before starting, preheat the oven to 450˚F. Wash and dry all produce. Cut potatoes into 1/2-inch wedges.Add potatoes, 1 tsp Indian Spice Mix and 1 tbsp oil to an unlined baking sheet. (NOTE: For 4 ppl, use 2 baking sheets, with 1 tbsp oil and 1 tsp Indian Spice Mix per sheet.) Season with salt and pepper, then toss to coat. Roast in the middle of the oven, flipping halfway through, until tender and golden-brown, 25-28 min. (NOTE: For 4 ppl, roast in the middle and top of the oven, rotating sheets halfway through.)

Meanwhile, halve buns.Finely chop cilantro.Cut radishes in half, then into 1/4-inch half-moons.Add radishes, cilantro, 1/2 tbsp vinegar and 1/4 tsp sugar (dbl both for 4 ppl) to a medium bowl. Season with salt and pepper, then toss to combine. Set aside.

Meanwhile, stir together mayo and 2 tbsp tikka sauce (dbl for 4 ppl) in a small bowl. Pat chicken dry with paper towels. Sprinkle 1/4 tbsp Indian Spice Mix (dbl for 4 ppl) over chicken, then season with salt and pepper. Heat a large non-stick pan over medium-high heat. When hot, add 1/2 tbsp oil (dbl for 4 ppl), then chicken. Sear until golden-brown, 2-3 min per side. (NOTE: It's okay if chicken doesn't cook all the way through in this step.)

Add remaining tikka sauce and 1/4 cup water (dbl for 4 ppl) to the pan with chicken.Reduce heat to medium. Cook, stirring sauce occasionally and flipping chicken halfway through cooking, until chicken is cooked through, 4-6 min.**Season with salt and pepper, to taste.Remove the pan from heat.

Arrange buns on another unlined baking sheet, cut-side up. Toast buns in the middle of the oven until golden-brown, 3-4 min. (TIP: Keep an eye on buns so they don't burn!)

Spread some tikka mayo on buns. Stack tikka chicken on bottom buns. Spoon any remaining sauce over chicken. Top with marinated radishes, then close with top buns.Divide chicken sandwiches and Indian-spiced potatoes between plates. Serve remaining tikka mayo on the side for dipping.