A VFR climb or descent; obviously. Either you must be able to maintain your own terrain separation below the minimum IFR altitude, or the controller can't clear you until you reach minimum IFR altitude (usually MVA for the controller), or a published route segment with a minimum altitude attainable with gauranteed clearance.
The controller isn't clearing you for an IFR enroute segment below IFR minimum altitudes, when asking if you can maintain your own terrain separation. The controller is clearing you to climb to a minimum altitude and asking if you can maintain your own terrain separation until that time. This presupposes that you will maintain adequate VFR cloud clearance and visibility at the same time.
The controller isn't clearing you for an IFR enroute segment below IFR minimum altitudes, when asking if you can maintain your own terrain separation. The controller is clearing you to climb to a minimum altitude and asking if you can maintain your own terrain separation until that time. This presupposes that you will maintain adequate VFR cloud clearance and visibility at the same time.
Simple. Don't go. Unless you can obtain the clearance, don't take off in those conditions. Go to town, make a call. Get on a cell. Send a carrier pidgeon and wait for it's return. Use a campbells soup can with a kite string. But get your clearance and void time before departing. It's a whole lot smarter and safer for you and everyone else involved.What do you do if its 500-2 at the departure airport? (Assume Class E since you don't need a clearance or flight plan to be IFR in Class G)