Peel and slice carrots lengthwise then cut each strip into 2 or 3 more lengthwise strips. Bunch together and cut strips into roughly ¼ inches producing diced carrots. Perfection not needed. If you’re lucky enough to have a gadget to do this, that’s great.
Dice the onion.
If you have a rice cooker, the rice into the cooker and add water (according to manufacturer’s recommendation) for rice only. Then place all other ingredients into cooker and stir to mix. Close cooker and allow to go through normal cooking time.
If you don’t have a rice cooker, put all the ingredients into a large pot. Add water to about one finger’s width above the contents in the pot and cover. Bring to a boil and immediately reduce heat to low and allow contents to steam for about 30 minutes.
Traditionally, when the rice is half cooked, it's divided in half, the carrots and onions are laid on the bottom half and the rest of the rice is then laid on top, hence "m'tubuq" meaning "layered". Cover again and continue to steam.