Grease and flour a 7 inch cake pan. Or Alternately grease and line with a butter paper. Set aside.
Preheat the oven to 180 C or 360 F for at least 15 mins. If using a OTG. both the heating elements (top & bottom) should be On or follow the Manual for baking a cake.
Sieve together flour, baking soda, baking powder & salt. If using wheat flour repeat the sieve twice more.
To another bowl, pour melted butter, sugar (optional), orange zest, orange juice, condensed milk & vinegar.
Whisk until uniformly mixed.
Add the flour little by little in batches to the liquid ingredients & mix until just combined.
Next add the flour in batches and mix. Avoid over mixing the batter.
Transfer this to the greased pan. Tap the pan to the counter twice to remove any bubbles.
Bake it for 24 to 28 mins or until a tester comes out clean.
Adjust the timing as needed. This depends on the oven used. When done completely, a tester inserted comes out clean.
Keep the cake pan for cooling on a rack for 10 mins and then remove it to the rack.
Cool Completely before frosting or slicing.
Grease & dust with flour a 8 inch cake pan or simply grease and line. Preheat the oven to 180 C or 360 F for at least 15 mins. If you do not have a 8 inch pan, then use a 6 inch pan and 2 ramekins.
Place a sieve over a large mixing bowl and add 1 ½ cups flour, ¼ tsp baking powder, 1 tsp baking soda and ⅛ tsp salt. Sieve the ingredients to the bowl.
Add ¾ cup sugar and 1 ½ tbsps orange zest. Mix everything well.
Pour ⅓ cup oil (80 ml), 1 cup orange juice & 1 tablespoon vinegar.
Gently mix with a spatula or a whisk to incorporate the dry ingredients into the wet.
Transfer the batter to the cake pan. Tap it to the counter twice to release any air bubbles.
Bake the orange cake for 24 to 27 mins. When the cake is fully baked, a tester inserted comes out clean. Bake a little longer if it is moist in the center. Adjust the timings as every oven is different.
Cool the eggless orange cake pan over a wired rack for 10 mins. Invert it over the rack and cool completely.