Place 1 tbsp of the oil, curry leaves, cumin seeds, black pepper, and red pepper flakes in a large frying pan over medium-high heat, stirring often, and cooking until the cumin seeds are fragrant and lightly browned, about 2 minutes. 

Add the onion and cook until translucent, 2 to 3 minutes, stirring often. Transfer the mixture to a bowl and set aside to cool. 

Place the ground turkey in a large mixing bowl and gently knead in the remaining ingredients. Stir in the onion mixture and form into four patties. 

Wipe out the frying pan with a paper towel/absorbent paper. Heat over medium-high for 2 minutes, add 1 tbsp oil, and then add the patties. Reduce the heat to medium and cook until browned, about 4 minutes. Flip and cook the other side until browned and the center is cooked to your preferred doneness (I like mine slightly pink). Place the burgers on the toasted buns, dollop with Raita and Tomato-Onion-Peanut Chutney, and serve. 

Raita:

Simple, soothing, healthful, and delicious, this is a staple at our home.

Place the cumin seeds, coriander seeds, and peppercorns in a small frying pan over medium heat and toast, shaking the pan often, until they're fragrant and the cumin is golden brown, about 2 minutes. Transfer the spices to a small plate to cool and then grind them using a spice grinder or coffee mill. 

Whisk the yogurt in a large bowl until it's smooth. Stir in the cucumber, onion, tomato, chiles (if using), and mint. Stir in the toasted spices and the cayenne. If serving immediately, stir in the salt and finish with the cilantro. Or cover with plastic wrap and refrigerate, stirring in the salt and cilantro just before serving. 

Tomato-Onion-Peanut Chutney:

Tomato chutney always finds a home on my table. This version is a little different because of the peanuts, which add a wonderful texture.

Heat the canola oil with the curry leaves, chiles, mustard seeds, and cumin seeds in a large frying pan over medium-high heat until the cumin is golden and fragrant, about 2 minutes. Stir in the turmeric and cook until the chiles darken, 1 to 2 minutes longer. Stir in the onions and cook until they have wilted and are opaque, 5 to 7 minutes. Stir in the peanuts, cook for 3 minutes, and then add the tomatoes, tomato paste, sugar, sambhaar powder, cayenne, and salt. Cook for 10 minutes, stirring often, pressing the tomatoes up against the sides of the pot to crush them. 

Reduce the heat to medium and cook until the tomato juices are reduced and the chutney is thick and jammy, stirring often, for 20 to 35 minutes (in the summer when tomatoes are juicy, it may take longer to thicken; in the winter, it may happen more quickly). Taste, adding more salt if needed, and then transfer to an airtight container and refrigerate for up to 1 week. 

Sambhaar Powder:

The southern Indian equivalent to garam masala, this blend tastes the most like what Americans and those across the pond might call "curry powder." I hold back on the amount of pungent fenugreek, but for a stronger and more traditional flavor, double it.

Place the chiles, coriander seeds, mustard seeds, cumin seeds, fenugreek seeds, urad dal, channa dal, pepper, and curry leaves (if using) in a medium frying pan over medium-high heat and toast, shaking the frying pan often, until the mustard seeds begin to pop, about 3 1/2 to 5 minutes. Transfer to a large plate to cool and then grind in a coffee mill or spice grinder. Store in an airtight container for up to 4 months.