Heat vegetable oil in a large stockpot over medium-high heat.
Saute onions and garlic.
Toss in chicken. Stir until cooked, they turn white.
Add opo. Stir well. Cover and cook for 5 minutes.
Uncover and slightly mix. Then add the tomato paste and stir well.
Add chicken stock. Use the whole box, then mix, stir to blend.
Add the rice noodles and submerge into the soup. Cover. Reduce heat to medium. Cook for 15-20 minutes.
Uncover and stir. Add salt and pepper. Stir well and taste. You can also use bouillon instead of salt. If not satisfied with the taste, and turn off the heat.
Serve with rice, bread or just the way it is.