ADD onion, garlic and bay leaf to a big pot with olive oil over medium-high heat.
LET simmer until onions are soft and garlic is browned but not burnt
ADD chicken to the pot. Season as desired with salt and pepper. Stir and cover.
ADD 6 cups water then cover again. Once boiling, add rice. Stir and cover again.
ADD chicken blood and vinegar to the pot, when rice is almost cooked through. Cook for another 10 minutes, covered, on low heat.
SERVE immediately while still hot.