Heat oil in a pan. (It would be good if you use non stick pan)
When the oil is hot add paneer pieces and fry it lightly on all sides.Take it out in a plate.
Now again in the same pan slightly fry the tomatoes.
Now add paneer cubes to the tomatoes.
Add the chaat masala, pepper, salt and lime juice as per your tastes and mix well.
Process to make it in oven:
Use the skewer/toothpick to arrange the paneer cubes and tomato and grill or you can simply place it in a baking tray with a tsp of oil and grill for 4-6 minutes till slightly cooked.
Remove from the oven and put paneer cubes and tomatoes in a salad bowl and add chaat masala, salt, pepper and lemon juice.
Mix it well and serve.
Notes
If you want you can use vegetable oil as well.
And you can also roast the paneer in the oven without oil.