Make the dough
To a large bowl, add flour, sooji, ajwain seeds and salt. Mix till well combined. Now add oil and mix with your fingers.
Now take some flour mix and press it tightly between your fingers. The dough should hold it's shape and not crumble apart. If dough crumbles, you need to add little more oil.
Add water little by little to form a tight but smooth dough. I used little more than 1/4 cup water for this. Cover the dough and let it rest for 30-40 minutes.

Prepare the filling
Soak urad dal in enough water overnight or minimum of 4 hours. Drain the water, rinse the dal and set aside.
Add the soaked and drained dal to a pan on medium heat. Add 2 cups of water to it, salt and pinch of turmeric powder.
Cook till the dal softens, but make sure it doesn't turn mushy. When you take a piece of lentil in between your fingers and press it, it should break easily, that's when you know it's done. This will take around 10-15 minutes.

Remove pan from heat, drain water and set aside.

To a pan add fennel seeds, coriander seeds and peppercorns. Dry roast till fragrant, around 4-5 minutes. Transfer to a spice grinder and grind coarsely.
Heat a pan on medium heat. Add oil to it, once the oil is hot add cumin seeds to it and let it splutter.
Add chopped ginger and green chilli and cook for 30 seconds.
Add the coarsely ground fennel-coriander mix and cook for a minute.
Add the cooked dal, salt, red chilli powder, amchur and mix till well combined.

Keep cooking till all the water from the dal evaporates. The stuffing should be totally dry. This will take few minutes. Remove pan from heat and set aside.

Make the kachoris
After the dough has rested, give it a quick knead. Divide the dough into 10-12 equal parts.Take one portion of the dough and shape it into a round ball.
Roll the dough ball a little and then make a well using your fingers. Fill with around 2 teaspoons of filling. Use your fingers to press the stuffing down.

Bring the edges together and seal the filling inside. You can use a paste made with flour and water to seal the edges if you are having problem with sealing them. Repeat till you have filled all the kachoris. You may be left with some extra stuffing, you can enjoy it with chai. Let the balls rest for 5-10 minutes before you roll them.
Now roll each filled kachori lightly. Kachoris are supposed to be small and thick so keep it thick. Also, roll very lightly or else the filling might come out.

It's for this reason, you should not over-fill the kachoris.

Meanwhile heat oil in a kadai/wok on high heat as you roll the kachoris. Keep all the rolled kachoris covered.
Once the oil is hot, drop the rolled kachoris carefully into the hot oil.

Fry all the kachoris in a similar way. Drain on a paper towel.
Serve hot kachori with any chutney of your choice.