Place the rice in a fine-mesh sieve and rinse under cold running water until the water runs clear. Set aside to drain.
Heat the olive oil or butter in a medium saucepan over medium heat.
Add the diced onion and cook, stirring occasionally, for 5–7 minutes until softened and translucent.
Add the garlic and cook for 1 minute. Then stir in the turmeric and cumin (if using) and cook for a further 30 seconds until fragrant.
Add the drained rice and stir to coat in the oil and spices. Cook for 2–3 minutes, stirring occasionally, until the edges of the grains look translucent.
Pour in the chicken or vegetable stock, add the bay leaf (if using) and salt, then bring to the boil.
Reduce the heat to low, cover with a tight-fitting lid and simmer gently for 15 minutes without stirring.
Remove the pan from the heat and leave, covered, for 10 minutes. Discard the bay leaf, fluff the rice with a fork and serve.