Yes, homemade rice porridge is a very good start. But it should be semisolid consistency.. not watery.
No doubt water is the most essential part of diet, but If you give more of rice- water, it subsides the hunger of the child without meeting the child's nutrition requirements. So better to give semisolid consistency rice porridge
Similarly some people also have habit of giving dilute 'Dal water', whih should be avoided, instead semisolid dal gives more nutrition.
You can add extra ghee to make it calorie dense.
Atleast 1/4th of a cup(200ml cup) should be given at one time for 2 to 3 times per day, along with continuing breast feeding
Cut and Squashed fruits,can be offered in between to the child. Extra
sugar can be added to make it calorie dense
Mashed potatoes
Remember to introduce only one type of food/dish at a time, so that if your child develops vomiting etc and there is intolerance to feed, that food can be easily identified and avoided
Moat important thing to know is , the food we start is not a substitute to breast feeding, rather it is complementary to breast feeding, which means breast feeding must be continued irrespective of what food you start the child on