Select the Sauté setting and heat the oil, butter, shallot, and garlicfor about 4 minutes, until the butter is melted, the shallots are softened,and the garlic is bubbling but not browned. Add the cherry tomatoes,thyme, and salt and sauté for about 2 more minutes, until the tomatoesare slightly softened. Add the wine, bring to a simmer, and cookfor about 3 minutes, until most of the wine has evaporated. Pour in thestock and bring to a simmer. Add the mussels to the pot, discarding anythat do not close to the touch, and stir to coat them in the cooking liquid.
Secure the lid and set the pressure release to Sealing. Press theCancel button to reset the cooking program, then select the PressureCook or Manual setting and set the cooking time for 2 minutes at lowpressure. (The pot will take about 10 minutes to come up to pressurebefore the cooking program begins.)
When the cooking program ends, perform a quick release by movingthe Pressure Release to Venting. Open the pot. Spoon the mussels intoa large, shallow serving bowl, discarding any that failed to open. Pourthe cooking liquid over the top.
Sprinkle with the parsley and serve right away, with the bread on theside for soaking up the cooking liquid.