Select SAUTÉ and adjust to LESS or LOW. Add oil, heat for 10-20 seconds, and tip in garlic and ginger; cook, stirring for a a few seconds only. Add onion, celery, and carrots. Continue cooking, stirring, for 2-3 minutes or until vegetables are softening. SELECT CANCEL/KEEP WARM.
Add remainder of ingredients except coconut milk, shrimp, and garnish: butternut squash - stock.
Close lid securely and close the PRESSURE-RELEASE VALVE. Select MANUAL and set for 10 minutes, pressure cooking.
When pressure cooking is completed, let sit cooling to use NATURAL RELEASE to depressurize--may take 20 minutes or more. Press CANCEL. Open the PRESSURE-RELEASE VALVE and allow steam to release. Open lid.
Purée using a hand-held immersion blender or carefully in batches in the food processor or blender (hold towel down tightly over lid). Select CANCEL/KEEP WARM. Select SAUTÉ and adjust to NORMAL. Stir in coconut milk and warm through, stirring. Taste and adjust seasonings. Select CANCEL/KEEP WARM. Serve hot garnished with a tablespoon of sour cream and fresh ground pepper or a teaspoon or so thinly sliced green onion and topped with grilled shrimp.