1. Peel and devein shrimp, reserving shells. Set shrimp aside.
2. Heat a medium saucepan over medium-high heat. Add 1 tablespoon oil to pan. Add shrimp shells; sauté 5 minutes. Add stock. Bring to a boil; cook until liquid is reduced to 1/2 cup. Strain liquid through a sieve into a bowl; discard shells. Reserve liquid.
3. Fill a large bowl with ice water. Bring 8 cups water to a boil in a large saucepan or Dutch oven. Add fava beans to pan; cook 1 minute. Remove with a slotted spoon. Plunge fava beans into ice water; cool completely. Drain well. Remove and discard tough outer shell from fava beans. Add green beans to boiling water; cook 2 minutes. Plunge green beans into ice water; cool completely. Drain well.
4. Heat a large skillet over medium-high heat. Add remaining oil and 1 tablespoon butter. Add garlic and shallots; sauté 2 minutes. Add corn; sauté 2 minutes. Add shrimp, reserved shrimp liquid, and salt; cook 3 minutes. Add fava beans, green beans, remaining 1 tablespoon butter, dill, tarragon, and hot sauce; cook 3 minutes or until shrimp are done. Remove from heat. Stir in sour cream and pepper.