Add the saffron threads to 3 tablespoons of warm water in a small bowl. Let bloom for at least 10 minutes.
Rinse the basmati rice in a fine mesh strainer under cold water until the water runs mostly clear. Drain well and set aside.
Heat the olive oil in a medium saucepan over medium heat. Add the diced onion and cook 4–5 minutes, until soft and golden at the edges.
Add the minced garlic and cook 30 seconds, until fragrant.
Add the rinsed rice and toast for 1–2 minutes, stirring constantly, until the edges look slightly translucent.
Pour in the vegetable broth and the bloomed saffron (including the water). Add the turmeric, bay leaf, and salt. Stir once and bring to a boil.
Reduce heat to low, cover with a tight-fitting lid, and simmer undisturbed for 15 minutes.
Check one grain for tenderness. If needed, cover and cook 2–3 minutes more.
Turn off the heat and let rest, covered, for 10 minutes.
Remove the bay leaf, stir in the lemon juice, and fluff gently with a fork. Top with chopped parsley and serve.