Use the Instant Pot's sauté function to soften garlic, leeks, and celery in olive oil before adding liquid—this builds a flavorful foundation that elevates the entire soup.

Dice all vegetables into similar-sized pieces (approximately ½-inch) to ensure even cooking under pressure and prevent some vegetables from becoming mushy while others remain firm.

Add quick-cooking vegetables like spinach and leafy greens after pressure cooking is complete—toss them in during the residual heat to maintain their texture and vibrant color.

Stir in fresh lemon juice just before serving rather than during cooking to preserve its bright acidity and prevent the flavor from becoming muted or bitter.

Allow 5-7 minutes of natural pressure release before quick-releasing to let carryover heat gently finish cooking the vegetables without turning them into mush.