Well, as a vegetarian, most of your food will contain carbs. The only things you eat that do not contain carbs (or very little) would be nuts/seeds and oils. All grains (rice/rava/etc.) vegetables, beans/legumes/dhal, fruits and dairy products contain carbs (ghee has very little, depending on how well it is clarified.)
In order to maintain your body (not get too thin) and have the nutrients you need to live, if you are vegetarian, you will be eating quite a few carbs. There's no way around that.
You'll need to figure out the carbs in the food you eat, and make substitutions that will keep you in energy balance.
For example, if you normally eat two cups of rice, eat one cup of rice and add 30 dry-roasted almonds to keep your calories the same while cutting carbs by a considerable amount (45 grams less.) Instead of a sweet rice dish, eat a bowl of dhal stew with no rice (more protein, fewer carbs.) Instead of a big serving of rava/upuma, have a small serving and add some vegetables sauteed in a little ghee to keep the calories the same.
You could start by cutting out the obvious: let go of sugar in tea, soft drinks, sticky desserts, canned fruit in heavy syrup, etc. Most tropical fruits are high in carbs. You'll need to do some research to see what you can have without spiking your blood glucose too high, but the first step is staying away from dried fruits (concentrated sugar) -- especially if they have been dipped in sugar-syrup -- also fruit juices/purees and canned fruit in syrup. Plain, natural, lower-carb whole fruits in small quantities will keep your carb-count down. For example a cup of canned fruit has 35 gm of carbs, while a medium kiwi has only 10 gm of carbs. Three ounces of banana chips have 45 gm of carbs, while three ounces of avocado has only 2-3 gm of carbs.