For Olive oil Frites: Pour 2 qt. olive oil into large 6-qt pot and heat over medium-low heat until it reaches 375 F. Add russet potatoes and cook until golden brown and crispy. Remove from oil with strainer; drain on paper towels. Season with salt, to taste.
For Mussels: Preheat large skillet over medium-high heat. Add 2 Tbsp olive oil to pan and sauté garlic, shallots and jalapeño until aromatic. Add mussels, Florida orange juice, tomato, lemon juice and pilsner beer. Season with salt and pepper, to taste. Cover and cook until mussels open fully.
Remove and discard any unopened mussels. Add butter and tarragon to mussels and toss until butter is melted.
Serve mussels in large bowl with Olive Oil Frites on the side.