A good source is Morrisons long grain brown rice. It is a converted rice and is much lower in calories than many other brown rices and it is quite low on carbs if you are careful with the other foods on the plate.
100g has 110 kcals, 19 gm carbs and 4 gm dietary fibre. I eat 75gm portions so about 80 kcals, 14 g carbs and 3 dietary fibre. 75 g is a good sized protion with a curry. If you make the curry using king prawns, fish or chicken, onions, garlic, ginger, chillis , some tinned tomatoes, corriander, cumin, garam masalla you have a tasty curry, satisfying to eat and probably around the 20g carbs. As your main meal of the day, it's not bad at all.
Not only can you vary the meats/seafood but you can add one of a number of other supplements such as fenugreek, cinammon or more chilli to vary the flavours.
Also high in dietary fibre is pearl barley which has a very low GI score. You can use pearl barley as a rice substitute in dishes like paella or risotto but it is great with soup and stews. This lamb and barley stew for example is full of fibre and kind on blood sugars.
http://www.theguardian.com/lifeandstyle/2011/mar/14/lamb-stew-pearl-barley-recipe
Add in broccoli and cauliflower and some beans and you'll be getting enough fibre.