Heat olive oil in a large skillet or paella pan over medium heat.
Add diced onion and cook until translucent, about 5 minutes.
Stir in minced garlic and diced bell peppers, cook for another 5 minutes.
Add diced tomatoes and cook until they start to break down, about 3 minutes.
Stir in the rice, vegetable broth, smoked paprika, and saffron threads. Bring to a boil.
Reduce heat to low, cover, and simmer for 20 minutes, or until the rice is cooked.
Stir in the frozen peas and artichoke hearts, cook for another 5 minutes.
Remove from heat, stir in lemon juice, and season with salt and pepper to taste.