Manchurian Cauliflower

For the Mustard Fenugreek Masala:
3 tablespoons coriander seeds
1 tablespoon cumin seeds
1 black cardamom pod
1 teaspoon fenugreek seeds
1 teaspoon cloves
½ stick cinnamon
½ teaspoon brown mustard seeds
½ cup dried chile de árbol
1 teaspoon whole black peppercorns
For the vegetables:
1 medium cauliflower
1 large carrot
1 yellow onion
1 tablespoon Mustard Fenugreek Masala
For the sweet and sour sauce:
1 cup tomato paste
1 cup granulated sugar
1 cup white wine vinegar
2 tablespoons ginger, minced
2 teaspoons Indian red chile powder
For the batter:
3 cups all-purpose flour
2 cups cornstarch
4 quarts rice oil (for deep-frying)
For the garnish
¼ cup cilantro, roughly chopped

To make the Mustard Fenugreek Masala:
Preheat the oven to 350° F. Measure out all the spices onto a sheet pan. Place the pan in the oven for 5 to 7 minutes until the spices begin to slightly smoke and turn a little brown. Remove the pan from the oven and set aside to cool. When the spices are fully cooled, grind them in a spice grinder in batches, until all spices are completely ground. Mix them well and keep in an airtight container for up to 4 weeks.
To make the vegetables:
Remove the outer green leaves and stems from the cauliflower, and cut the head down the middle in an X to make four wedges. Lay the wedges cut-side down and make thin cross-sectional slices of each piece. After cutting a cauliflower wedge about halfway, turn the piece and chop the rest of the wedge into bite-size florets. This cutting technique provides different textures of cauliflower.
Peel the carrot and cut it on the bias into thin slices about 2 inches long.
Halve and peel the onion. Cut half moon slices of onion.
Mix all the vegetables together and season with the Mustard Fenugreek Masala, black salt, chili powder, and kosher salt. Set the vegetables aside for 2 to 4 hours.
To make the sweet and sour sauce:
Combine the tomato paste, sugar, vinegar, ginger, and chili powder in a medium saucepan on medium-high heat. Bring to a boil, lower the heat, and simmer for about 15 minutes, stirring occasionally. Remove from the heat.
To make the batter:
Combine the flour and cornstarch in a large bowl. Pour 5 cups of water into the bowl a cup at a time and mix with a large whisk until a thick runny pancake batter consistency is reached.
For the first fry:
Heat the oil for deep-frying to 300°F in a heavy-bottom pot. Check the temperature with a thermometer. Dip the cauliflower mix into the batter in batches and drop into the hot oil. Use a mesh “spider” or slotted spoon to move the cauliflower mixture around to keep it from forming large clumps. When the mixture begins to lightly brown—about 3 minutes—remove and place the cauliflower on paper towels to drain any excess oil. Continue cooking the cauliflower mixture in batches. Compost any excess batter.
To finish and assemble the dish:
Increase the heat in the fryer to 375°F. Check the temperature with a thermometer. Drop the fried cauliflower mix back into the hot oil for about 5 minutes, until golden brown and crispy. Remove the cauliflower from the oil. In batches, toss the cauliflower mix in a metal bowl with the sweet and sour sauce. Garnish with the cilantro.