This is how it may look like.
1. Protein (poultry, red meat, eggs etc) - 1 palm size or 1 hand size
2. Carbs (brown rice, sweet potato etc) - 1 fist size
3. Veg (go for more greens like broccoli, bok choy, long beans etc) - 2 handful
If you think it's not enough, you can add more greens, greens are practically "free foods," them fibers shall fill you up more. You can make some tweeks to this measurement depending on your goal, some people are trying to hit that 1 digit body fat, so they would take out the carbs completely and replace it with more vegs.