In a large saucepan, combine the green split peas with enough water to cover them by about an inch. Bring to a vigorous boil over medium-high heat, then cook for 15 minutes. Drain and set aside.

Peel and chop the gold potatoes into bite-sized pieces. Cook in salted boiling water for about 7 minutes, then drain.

Heat olive oil and sauté onion and garlic for about 5 minutes until fragrant and golden.

Stir in cumin, black pepper, and cayenne pepper. Cook for an additional minute.

Add par-cooked potatoes, drained split peas, vegetable broth, and chopped celery. Bring to a gentle boil, reduce heat, cover, and cook for 20-25 minutes until tender.

Blend the mixture until smooth. Adjust texture as desired.

Stir in lemon juice, adjust seasoning with salt and pepper, and serve hot, drizzled with olive oil and za'atar if desired.