Stuff each one with the rice mixture making sure not to reach the top, so basically you want to leave about ½ cm of the top of your vegetable. Rice will expand after cooking and if you are overstuffing the tomato, rice will come off. Not that it will taste bad but the presentation will not be as fancy.
Arrange herbs stems, the inside of your tomatoes that you just took out, lemon slices, tomato slices or onion slices at the bottom of your cooking pot to prevent scorching. Arrange the stuffed tomatoes in your pot.
Dissolve bouillon and tomato paste in the hot water. Pour into the pot so that the cooking liquid is halfway through the tomato layers. Place pot on medium high, bring to a boil then reduce heat and simmer for 40 minutes until tomatoes and rice are cooked.
Wait for it to cool down a bit and serve!