You can avoid oxalate containing food like spinach, cabbage , black tea/coffee, chocolates, avoid to Amari seed, tomato pulp can be consumed, sprouts . These are main food you can take lesser, it’s not like if you are going to take once in 15-20 days than it will form stone. Most important things is take plenty of oral fluids. 1.5-2 litres/day in winters and 3.5-4 litres per day in other seasons.